My late 2009 iMac 27" will not boot completely

My late 2009 iMac will not boot-up completely. I get the little clock/second hand thingy on a white background, but no matter how long I let my machine try to boot, it still will not boot. Is there a "Safe" mode to possibly to boot into to get my iMac straightened out? Any other thoughts to try?

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You bet, have a look at > Mac OS X: Starting up in Safe Mode
and/or > Mac OS X: Gray screen appears during startup

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Late 09 iMac 27 will not boot up then shuts down

Second occurrence of this issue in roughly 2 months:
1st time: pre-Mavericks
2nd time: after HD reformat and Mavericks install, both at Genius Bar
I get the tone, logo, gear, progress bar to roughly 10%, then shutdown. I cannot even get into safe mode or try disk utility. The various resets (pram, etc...) do not work either
I took it to the genius bar and they reformatted the HD and all was well for a couple of months. I do not have any 3rd party SW except for iBank, MS Office, and printer drivers. As with the first time this popped up, I had a couple of warning reboots before this. I was able to save my large iPhoto file.
So, is this a HW issue? If not what SW problem would cause the same issue again if the HD was reformatted once already?
Debating pitching the iMac and going Mac Mini, all we use the Mac for is finances,email, and iPhoto.
Thanks for any thoughts or suggestions.

Welcome to Apple Support Communities
You bet, have a look at > Mac OS X: Starting up in Safe Mode
and/or > Mac OS X: Gray screen appears during startup

My iMAC 24 will not boot up, I only get a blue screen

My iMAC 24 will not boot up, all I get is a blue screen. I loaded my install disk but the problem remains the same.

Failed hardware, take it in for service.

White 2008 MacBook will not boot completely (hangs up)

For Christmas 2008 I bought a New 2008 Apple MacBook (White) for my 13 year old Grandson. He gave it back to me to "fix" .
He said the following problem ----will not boot/Hangs UP during boot---- *first appeared immediately after he downloaded and installed an "APPLE/MACBOOK" update of some kind last week.*
DOES THIS SOUND FAMILIAR TO ANYONE OUT THERE? IF SO I WOULD APPRECIATE YOUR SUGGESTIONS.
More info:
It will not boot completely. when powered on it-- chimes once with the normal Mac sounds (Not a POST Beep error)---- and a white screen---- with apple logo in center appears--- after several seconds a small spinning "activity/busy" circle appears below the logo. This circle appears and spins for about 3 to 4 minutes with no other activity happening. Then the screen goes blank and power goes off.
Oh yes I am not certain as to the Exact OS designation that is installed (sorry)
I am new to Mac but have checked:
The power (A/C, and supply are on, Mag power cord attached and battery charge light on battery is blinking green with 4 steady green lEDs on--- (So I assume I'm OK with NO power or battery issues)
I then tried to boot into "safe" mode. (shift key when power on) (No change)
Then I tried Cmd, Option, P, R keys as suggested in manual during power on to reset nv(p)Ram (No change)
Grandson is searching for manuals, OS Apple Hardware troubleshooting disk etc. While I wait to receive those items from him --------
Does anyone have any Ideas /suggestions?
Thanks in advance!
Joe

HI Joe and Welcome to Apple Discussions...
Since you can't boot in Safe Mode that's not a good sign. You really need those install disc(s) to repair the drive if necessary.
When you get the install disc...
Insert the installer disk and Restart, holding down the "C" key until grey Apple appears.
Go to Installer menu (Panther and earlier) or Utilities menu (Tiger and later) and launch Disk Utility.
Select your HDD (manufacturer ID) in the left panel.
Select First Aid in the Main panel.
(Check S.M.A.R.T Status of HDD at the bottom of right panel. It should say: Verified)
Click Repair Disk on the bottom right.
If DU reports disk does not need repairs quit DU and restart.
If DU reports errors Repair again and again until DU reports disk is repaired.
When you are finished with DU, from the Menu Bar, select Utilities/Startup Manager.
Select your start up disk and click Restart
While you have the Disk Utility window open look at the bottom of the window. You will see Capacity and Available. Make sure you always have a minimum of 10% free disk space.
You can try something that doesn't require the install disk and that's Reset the SMC
If you can get the MacBook to boot up to the Desktop, click the Apple Menu then click About This Mac. The Mac OS X version number will be displayed there. 10.x.x
Carolyn

2009 Mac Pro will not boot up under Windows

I have an Early 2009 Mac Pro system (Mac Pro 4,1) and I've had this system for 3 years already and have been working under OS X with this system ever since I purchased it.
However, when I tried to boot off my Windows disk, something very interesting happens. The Mac Pro WILL NOT boot up off the Windows disk or a known working Windows partition if two monitors are connected. Upon holding down the option key and selecting the Windows partition, I will get a black screen on one monitor (the one connected via Mini Displayport) and the other screen receives no signal and will enter standby and the system is halted. It does not respond to keystrokes, there is no hard drive activity, no measured power increase on the UPS, no apparent network activity, nothing. The only way to exit this scenario (from what I can tell) is to power off the machine, disconnect the display on DVI, power on the machine again, select the Windows partition wait for the system to reach the login window and reconnect the DVI monitor (at which time Windows recognizes it immediately and the system works fine again).
My question to the community is, does anybody know why this is happening and is there a known fix for this? Quite frankly, having to disconnect a monitor just to restart is very tedious and frustrating.
I have two Samsung P2350 monitors attached to an ATI Radeon HD 4870 (512MB, from Apple). One is monitor is connected via directly DVI and the other is using a Mini Displayport to DVI adapter. Both monitors work fine under OS X with no issue. At first, I thought that this may be a driver issue on the Windows side and after installing all the latest updates and drivers the issue is still apparent. From what I can tell, this doesn't seem like a software issue but rather a firmware or EFI issue as this happens before Windows even loads.
If anyone knows of a fix or what to do in this situation, or if you are also having this issue, I would love to hear your input!
Thank you!
For the record, I am running all the latest software builds on the OS X side (10.7.4, not that it would really matter at this point). I have also disconnected all unnecessary equipment in a trial and error scenario but the results are still the same.
The system passes all ASD testing.
The full specification of the computer and all connected equipment are as follows:
2009 Mac Pro (4,1) 8-Core
2x Intel Xeon Nehalem 2.66GHz Quad-Core CPUs
16GB DDR3 ECC 1066MHz RAM (Apple Branded)
Two OWC 120GB SSDs (One for OS X, the other for Windows 7 x64) - These are in place of my optical drives.
4x 2TB WD Black Hard drives for storage.
Two Samsung P2350 Monitors connected via DVI. (One using a Mini Displayport to DVI adapter).

In Windows I am using the latest (12.4) Catalyst Software Suite, 64 bit of course, downloaded directly from AMD's site after installing the drivers from Boot Camp.
As for installing Windows I used an original (not burned) installation media (Disk is in a pristine condition). And yes, Windows is fine, the problem just seems to be getting the system to boot up Windows with that second monitor. However if the "problem monitor" is disconnected the system boots fine 100% of the time and connecting it later after booting the system will still operate properly.
For the sake of arguement I swapped monitor cables and connected the "second" monitor to the mini displayport adapter to verify that it wasn't a cabling issue and I'm still yielding the same issues.
As for GPU testing, I've played games (Crysis, Grand Theft Auto IV, Battlefield 3, etc.) and I've had no issues with the card or stability.
You would think that Apple would try to find a fix for this, especially considering the caliber of this machine.

Should I do a clean install of Mountain Lion on a late 2009 iMac or will I find hardware/driver issues?

I have a late 2009 iMac (2.93 Ghz Intel Core Duo, 4GB of ram, model id is 9.1) running Lion right now. I upgraded it all the way from Leopard using the standard keep-all-your-apps-and-settings way. After looking at the hardware requirements for Mountain Lion (and my success with running Lion) it seems that my good ol' iMac is still capable of running it fairly well. But I don't like the idea of "stacking" upgrade after upgrade (*coughs*, clean freak!). I like the idea of starting out clean this time because so many years of use has filled my mac with a lot of crap I no longer use.
So I would like to know your sane advice, and if there's anything I should check out before attempting this. Especially I'm concerned about hardware/driver related issues like for example: the webcam or speakers no longer working. Also, if there's something I'm overlooking please point it out.
Thank you in advance for any help you guys can give me. I'll be very grateful!

If it wasn't a Mac computer that originally came with either Lion or Mt Lion Pre-Installed by Apple when new you would not be able to connect to the Online Internet Recovery system. It is a Feature of the Mac EFI Firmware system. And it will only install whichever version of the Download only version of OS X that originally came on that system.
My MBP came with Lion Preinstalled. Even if I have Mt Lion installed on the hard drive the Online Internet Recovery system would always point my MBP to the Lion download as that was the original version of OS X that came on my Mac.
No real authentication needed. Since your Mac came with Mt Lion no matter what newer versionof OS X you ever install the OIRS will always point you to Mt Lion and ONLY Mt Lion.
It is something different, but not completely different, from the built in Recovery HD partition on the internal drive.
No worries as during the install of MT Lion on your SSD the installer will Recreate the Mt Lion Recovery HD partition on your SSD.

IMac G5 will not boot and if it does, it does not display any logo

Hi everyone, any assistance with this issue would be greatly appreciated. This is my godmothers iMac G5 that my family gave her a few years ago, it is the 2.0GHz model with no iSight camera but has the built in WiFi and Bluetooth.
I went to start it today, after it being off for a week and a half and it will not boot. I start it up and it displays the solid white LED light on the front and revs its fans until I stop it. I got it to get past this once by resetting the SMU but all it did was make the Apple hardware test sound noise and get a blank white screen. No Apple logo or anything. Entire time it rev'd its fans.
Thank you! If it is broken I will most likely sell it for parts and either buy her an older unibody MacBook or wait for the next-gen iPad with FaceTime and a buy a keyboard dock.

HI and welcome to Apple Discussions...
If you have the install disc that came with this G5, try checking the startup disk for errors.
Insert your install disk and Restart, holding down the "C" key until grey Apple appears.
Go to Installer menu and launch Disk Utility.
(In Mac OS X 10.4 or later, you must select your language first from the installer menu)
Select your HDD (manufacturer ID) in the left panel.
Select First Aid in the Main panel.
(Check S.M.A.R.T Status of HDD at the bottom of right panel. It should say: Verified)
Click Repair Disk on the bottom right.
If DU reports disk does not need repairs quit DU and restart.
If DU reports errors Repair again and again until DU reports disk is repaired.
When you are finished with DU, from the Menu Bar, select Utilities/Startup Manager.
Select your start up disk and click Restart
While you have the Disk Utility window open, look at the bottom of the window. Where you see Capacity and Available. Make sure there is always 10% to 15% free disk space
If it won't boot from an install disc, try booting in Safe Mode Launch Disk Utility (Applications/Utilities). It's possible to do a live verification in Safe Mode to check the startup disk for errors, but not repair disk but at least you might get some insight as to the problem.
Carolyn

Brand New 27" iMac i5 will not boot after installing software updates

I just purchased my new iMac 2 nights ago. I have been getting it setup with my apps, mobile me account, etc, and luckily just setup time machine and let it do a full backup.
I just ran Software Update for the first time, and now the machine will not boot. It hangs on the grey screen for about 1 minute before the Apple logo comes up. About 30 seconds after the Apple logo comes up, the grey spinning gear shows up, and about 1 minute after that I get the grey screen of death (You must restart your computer).
Any suggestions? A little frustrated here....

If you mean did I receive error messages, No, I didn't. However, the desktop reverted to the default purple night-sky looking thing, my applications and such all disappeared from the dock, and I couldn't open any files or folders (you don't have permission to ...), etc. I tried signing out and back in, rebooting, using a second admin account on the computer, creating a new admin account, etc. I ran Disk Utility, hardware checker, etc. No errors were found, and nothing changed. I could see all my files and folders, but they had a small red circle in the corner, indicating "locked" or "no permission".
I'll find the lines from the console log if that will help. The error showed up immediately and is in the computer's attempt to access the user/library/application support/sync services and same path to user/library/logs/sync services/log. (or something reasonably close to this. If you can use the exact path, I will get it) The link between my settings and files, and a password is apparently corrupted or something, so that the computer won't even let me change the desktop or any file, so I can't save, edit or discard anything, and can't drag files to another computer on the home network.
At least I'm still under the 90 day warranty, so I can call tomorrow. At this point, the SMART check says the drive is good, so I assume it's software. The only things new are the three auto Apple software updates I installed yesterday, so I immediately suspect them. But who knows?
Does this help you at all?

Late 2011 17" MBP - Will not boot, eject, or read disk

Hi guys,
My late 2011 17" MBP after having a server error on Mac Recovery, freezing, and being force shut off, now will not boot.
When you power it up, it chimes then goes to a blue screen, indefinitely.
It also will not eject the DVD in it's drive.
I've tried every key combination prior to startup or during startup to try and remedy this, and nothing.
It always boots with a chime then blue screen.
Please help. :3

Ejecting the disk:
Try these various remedies: http://guides.macrumors.com/Force_Eject_a_Stuck_CD_or_DVD
Since your Mac came with Lion installed it may have a recovery partition on the boot disk.
There are two ways boot from the Recovery Partition:
- Hold down the Command-R as you boot.
          This will attempt to boot from the Recovery Partition
          and if that fails it will try to boot using Network Recovery (a slow process).
- If it won’t boot using Command-R then hold down the Option key as you boot.
          Select the Recovery Partition.
Backup: Do you have a recent backup? If not I suggest you create one before proceeding. You might not need it but it is especially important to have a backup whenever your Mac is sick. Post back for instructions for an emergency backup, if needed.
Blue Screen:
From the Recovery Partition you should be able to repair the disk and reïnstall OS X (without erasing you existing data).

My 2009 macbook pro will not boot up I have installed Yosemite

My laptop will not boot up. I have tried to repair the disk but I keep getting error mesages that the edisk needs to be installed because files are missing.

Do a backup. Boot to the Recovery Volume (command - R on a restart or hold down the option/alt key during a restart and select Recovery Volume). Run Disk Utility Verify/Repair and Repair Permissions until you get no errors. Then re-install the OS.
OS X Recovery
OS X Recovery (2)

Imac G5 will not boot, Grey screen. Please help!

Please forgive me if this posting is a bit lengthy!
My Mac had been on sleep mode for 2 days, when I tried to wake it up a message popped up stating that a system failure had occurred (Darwin Kernal version 7.7.2: etc). I shut it down and tried to restart only to get a grey screen and with the spinning gearlike timer and after about a minute the fan started to run at full power upon which I turned it off via the power button on the rear. I tried several times to re-boot but the same thing happened each time.
I have tried to start up using the ‘safe-boot’ mode (held down shift after chime and released upon seeing Apple logo and spinning gear timer). After a few seconds however, the screen goes blank and the start-up chime repeats only to be followed once again by the grey screen, spinning gear and fan running at full speed. No progress
The Apple website suggests using the ‘Software Install or Restore’ disc which came with the computer. However, I don’t have this disc, only ‘Apple hardware test’ and ‘Mac OSX Install’ (3 discs) came in the box.
I checked the system using the ‘Apple Hardware Test’ CD (by holding down the C-key during start-up) using both the quick and advanced check but no problems were reported.
I then ran Disc Utility from the first installation disc to repair permissions on the HD which was successful. However, after re-starting the machine, once again the same grey screen appeared with no apparent progress.
I then tried to check for damage using the ‘fsck’, recommended by Apple if ‘safe boot’ mode cannot be run. After starting up in single-user mode I typed the following prompt: /sbin/fsck –fy. It ran through a quick phrase list but then delivered the line ‘Volume Check Failed’. I faired no better when I repeated the process over again.
I have never updated the software with Apple updates since I bought the machine (don’t laugh), mainly because I don’t have a broadband internet connection at home, could there be a bug in Panther OSX that needed fixing with a later update?
I have no ‘add-ons’ plugged in other than the keyboard and mouse. I don’t think it can be a firmware problem, I am the only user and have not changed any settings relating to access permissions.
This is my first Mac and so my experience of problem solving is quite limited. I am not a Mac expert and to be honest am confused by much of the jargon. The computer is now two years old and therefore out of warranty so I don’t want to take it to my local Mac shop if I can solve the problem myself.
I’m a bit concerned as there are many documents that I have not backed-up (foolish I know).
I don’t know how I can attempt to rectify anything if the machine will not even boot-up in safe mode!?!
Could the problem be something to do with the PRAM settings, might the internal battery be dead bearing in mind that the machine is now 2 years old?
Would it be possible to re-install Panther from the original discs, I have read that this will not loose any files but can somebody confirm this?
Can anybody offer some advice as to what I might try to get the Mac to start-up and avoid any problems in the future? Any advice will be much appreciated.
Imac G5 Mac OS X (10.3) 80Gb HD / 768Mb RAM

Please accept my apologies regarding the time it has taken for me to get back to you. Since we last spoke I have been away on vacation.
Upon my return I attempted to follow your advice but it would seem that my problems are more significant than I had originally anticipated.
First, as you recommended I reset the PRAM by holding down the required keys from start-up, until the machine re-started.
I then attempted to perform the ‘Archive and Install’ process for OS10.3 (Panther) from the original software discs, making sure to select ‘Preserve User Settings and Preferences’.
My Mac first went through a ‘Checking your Installation Disc’ phase (10 mins) before starting the next phase ‘Checking Target Volume Consistency’. However, after only a few seconds it stopped with the pop-up message ‘There were errors installing the software’. I repeated the process but got the same message.
I decided to run Disc Utility once again from Disc 1, upon which I realised that I had previously only run Verify & Repair Disc Permissions, not Verify Disc or Repair Disc.
I decided to try to Verify Disc under First Aid, however, this was where the trouble started. I got the following message on screen:
"The Volume Macintosh HD needs to be repaired.
Volume Check Failed
Error: The Underlying task reported failure on exit (-9972)
1 Volume checked
HFS Volumes verified
1 Volume failed verification."
Obviously I am assuming this problem is preventing me from performing an ‘Archive and Install’. Now I’m a bit concerned that my problem could be very serious, bearing in mind that so many of my files are not backed up.
I’d be very grateful for more wise advice as to what to try next.
Imac G5 Mac OS X (10.3) 80Gb HD / 768Mb RAM
Imac G5 Mac OS X (10.3) 80Gb HD / 768Mb RAM

Imac Intel will not boot up - 3 days old, light on, starts to spin...

I got an Imac Intel 20" from my husband on mother's day and it now will not turn on!! White light comes on, sounds like it is trying to boot and then nothing... blank screen, no beeps - have unplugged and restarted, tried a million key combination from the forums and still nothing... locked up once on "Garage?" software (according to son)... worked for 2 days...
Very dissapointed and sad... husband looking like the PC is still a better box even after breaking down and getting the Imac - can't help much because this is all new to him...
Help!

If you bought your imac with a credit card anywhere in your home state(or within 100 miles of your home in another state), then you can return it within 30 days if you are unsatisfied. That is federal law, and a store cannot do anything to deprive you of those rights--no matter what they say (or what they print on the receipt under your signature). My Apple store tried to tell me they only allow returns for 2 weeks. I told them the were violating federal law and they were required to issue a credit for the amount of the return, and they reluctantly complied.
I believe credit card companies are now required to print those rules on your bill (mine does and I don't think it would do so voluntarily), so you can check the fine print on your last bill and read them.
So, if you meet the above requirements, take your imac back . Insist on a refund. Be firm. If the retail person won't do it, tell them you want to speak to a manager. Once they credit your account, walk up to another retail person and tell them you want to buy a 20" imac.
If the retailer won't credit your account, then call your credit card company, and tell them you tried to return a defective product within the 30 day limit that you bought in your home state, and you would like them to reverse the charges.

IMac, 2010, will not boot after update

After downloading Yosemite, my 2010, 27" iMac will not reboot. It appeared to install ok but it stayed white screen, no text for more than an hour after it automatically rebooted. Idaes?

Take each of these steps that you haven't already tried. Stop when the problem is resolved.
To restart an unresponsive computer, press and hold the power button for a few seconds until the power shuts off, then release, wait a few more seconds, and press it again briefly.
Step 1
The first step in dealing with a startup failure is to secure the data. If you want to preserve the contents of the startup drive, and you don't already have at least one current backup, you must try to back up now, before you do anything else. It may or may not be possible. If you don't care about the data that has changed since the last backup, you can skip this step.
There are several ways to back up a Mac that is unable to start. You need an external hard drive to hold the backup data.
a. Start up from the Recovery partition, or from a local Time Machine backup volume (option key at startup.) When the OS X Utilities screen appears, launch Disk Utility and follow the instructions in this support article, under “Instructions for backing up to an external hard disk via Disk Utility.” The article refers to starting up from a DVD, but the procedure in Recovery mode is the same. You don't need a DVD if you're running OS X 10.7 or later.
b. If Step 1a fails because of disk errors, and no other Mac is available, then you may be able to salvage some of your files by copying them in the Finder. If you already have an external drive with OS X installed, start up from it. Otherwise, if you have Internet access, follow the instructions on this page to prepare the external drive and install OS X on it. You'll use the Recovery installer, rather than downloading it from the App Store.
c. If you have access to a working Mac, and both it and the non-working Mac have FireWire or Thunderbolt ports, start the non-working Mac in target disk mode. Use the working Mac to copy the data to another drive. This technique won't work with USB, Ethernet, Wi-Fi, or Bluetooth.
d. If the internal drive of the non-working Mac is user-replaceable, remove it and mount it in an external enclosure or drive dock. Use another Mac to copy the data.
Step 2
If the startup process stops at a blank gray screen with no Apple logo or spinning "daisy wheel," then the startup volume may be full. If you had previously seen warnings of low disk space, this is almost certainly the case. You might be able to start up in safe mode even though you can't start up normally. Otherwise, start up from an external drive, or else use the technique in Step 1b, 1c, or 1d to mount the internal drive and delete some files. According to Apple documentation, you need at least 9 GB of available space on the startup volume (as shown in the Finder Info window) for normal operation.
Step 3
Sometimes a startup failure can be resolved by resetting the NVRAM.
Step 4
If a desktop Mac hangs at a plain gray screen with a movable cursor, the keyboard may not be recognized. Press and hold the button on the side of an Apple wireless keyboard to make it discoverable. If need be, replace or recharge the batteries. If you're using a USB keyboard connected to a hub, connect it to a built-in port.
Step 5
If there's a built-in optical drive, a disc may be stuck in it. Follow these instructions to eject it.
Step 6
Press and hold the power button until the power shuts off. Disconnect all wired peripherals except those needed to start up, and remove all aftermarket expansion cards. Use a different keyboard and/or mouse, if those devices are wired. If you can start up now, one of the devices you disconnected, or a combination of them, is causing the problem. Finding out which one is a process of elimination.
Step 7
If you've started from an external storage device, make sure that the internal startup volume is selected in the Startup Disk pane of System Preferences.
Start up in safe mode. Note: If FileVault is enabled in OS X 10.9 or earlier, or if a firmware password is set, or if the startup volume is a software RAID, you can’t do this. Post for further instructions.
Safe mode is much slower to start and run than normal, and some things won’t work at all, including wireless networking on certain Macs.
The login screen appears even if you usually log in automatically. You must know the login password in order to log in. If you’ve forgotten the password, you will need to reset it before you begin.
When you start up in safe mode, it's normal to see a dark gray progress bar on a light gray background. If the progress bar gets stuck for more than a few minutes, or if the system shuts down automatically while the progress bar is displayed, the startup volume is corrupt and the drive is probably malfunctioning. In that case, go to Step 11. If you ever have another problem with the drive, replace it immediately.
If you can start and log in in safe mode, empty the Trash, and then open the Finder Info window on the startup volume ("Macintosh HD," unless you gave it a different name.) Check that you have at least 9 GB of available space, as shown in the window. If you don't, copy as many files as necessary to another volume (not another folder on the same volume) and delete the originals. Deletion isn't complete until you empty the Trash again. Do this until the available space is more than 9 GB. Then restart as usual (i.e., not in safe mode.)
If the startup process hangs again, the problem is likely caused by a third-party system modification that you installed. Post for further instructions.
Step 8
Launch Disk Utility in Recovery mode (see Step 1.) Select the startup volume, then run Repair Disk. If any problems are found, repeat until clear. If Disk Utility reports that the volume can't be repaired, the drive has malfunctioned and should be replaced. You might choose to tolerate one such malfunction in the life of the drive. In that case, erase the volume and restore from a backup. If the same thing ever happens again, replace the drive immediately.
This is one of the rare situations in which you should also run Repair Permissions, ignoring the false warnings it may produce. Look for the line "Permissions repair complete" at the end of the output. Then restart as usual.
Step 9
If the startup device is an aftermarket SSD, it may need a firmware update and/or a forced "garbage collection." Instructions for doing this with a Crucial-branded SSD were posted here. Some of those instructions may apply to other brands of SSD, but you should check with the vendor's tech support.
Step 10
Reinstall the OS. If the Mac was upgraded from an older version of OS X, you’ll need the Apple ID and password you used to upgrade.
Step 11
Do as in Step 9, but this time erase the startup volume in Disk Utility before installing. The system should automatically restart into the Setup Assistant. Follow the prompts to transfer the data from a Time Machine or other backup.
Step 12
This step applies only to models that have a logic-board ("PRAM") battery: all Mac Pro's and some others (not current models.) Both desktop and portable Macs used to have such a battery. The logic-board battery, if there is one, is separate from the main battery of a portable. A dead logic-board battery can cause a startup failure. Typically the failure will be preceded by loss of the settings for the startup disk and system clock. See the user manual for replacement instructions. You may have to take the machine to a service provider to have the battery replaced.
Step 13
If you get this far, you're probably dealing with a hardware fault. Make a "Genius" appointment at an Apple Store, or go to another authorized service provider.

IMac G4 will not boot. It shows only a gray screen, but without the spinning wheel.

Hi Everyone,
I tried to use my Imac G4 1.25Ghz today, after it had been stored for about a year.
It will only show the gray screen with the apple logo, but with no "spinning wheel"
I have tried "Command-Shift-P-R" immediately after pressing the power button, but nothing changes.
Searching on line leads me to believe it could be the internal battery. Is this likely?
If so, are all "half AA" Lithium batteries suitable? I have found the info for changing it on line, but would like some confirmation as to how to replace it.
If not, what else can I try? Please explain in laymans language if possible as I'm not a techy! (but have a friend who can help me if needed)
I can't remember what version of OSX it is running, other than it is Panther.
The install/restore discs say 10.3.2 (but I thought it was more recent).
Cheers
Tim

Although a dead internal backup battery could be the cause, you might first try reinstalling OS X:
How to Perform an Archive and Install
An Archive and Install will NOT erase your hard drive, but you must have sufficient free space for a second OS X installation which could be from 3-9 GBs depending upon the version of OS X and selected installation options. The free space requirement is over and above normal free space requirements which should be at least 6-10 GBs. Read all the linked references carefully before proceeding.
1. Be sure to use Disk Utility first to repair the disk before performing the Archive and Install.
Repairing the Hard Drive and Permissions
Boot from your OS X Installer disc. After the installer loads select your language and click on the Continue button. When the menu bar appears select Disk Utility from the Installer menu (Utilities menu for Tiger, Leopard or Snow Leopard.) After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list. In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive. If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button. Wait until the operation completes, then quit DU and return to the installer. Now restart normally.
If DU reports errors it cannot fix, then you will need Disk Warrior and/or Tech Tool Pro to repair the drive. If you don't have either of them or if neither of them can fix the drive, then you will need to reformat the drive and reinstall OS X.
2. Do not proceed with an Archive and Install if DU reports errors it cannot fix. In that case use Disk Warrior and/or TechTool Pro to repair the hard drive. If neither can repair the drive, then you will have to erase the drive and reinstall from scratch.
3. Boot from your OS X Installer disc. After the installer loads select your language and click on the Continue button. When you reach the screen to select a destination drive click once on the destination drive then click on the Option button. Select the Archive and Install option. You have an option to preserve users and network preferences. Only select this option if you are sure you have no corrupted files in your user accounts. Otherwise leave this option unchecked. Click on the OK button and continue with the OS X Installation.
4. Upon completion of the Archive and Install you will have a Previous System Folder in the root directory. You should retain the PSF until you are sure you do not need to manually transfer any items from the PSF to your newly installed system.
5. After moving any items you want to keep from the PSF you should delete it. You can back it up if you prefer, but you must delete it from the hard drive.
6. You can now download a Combo Updater directly from Apple's download site to update your new system to the desired version as well as install any security or other updates. You can also do this using Software Update.

Imac G5 will not boot up. there is power but the screen is black. About 30 sec after turning it on, the fan comes on loudly.

I have an old imac G5 (non Intel) The screen went blank but the fan turns very loudly. I cannot reboot the computer. whenever I start it I get power and black screen and the fan comes on loudly after about 30 secs. I have tried rebooting pressing varius keys, but no luck. I once got the flashing question mark, but I can't get that either. I'd like to reboot from the disc, but I cannot insert a disc. Any help out there??

If zapping the PRAM does not get it working, it's time for a new iMac. Repairs will not be worth the cost. Put it towards a new iMac.
I've been there, done that. Had my burial last summer.

My late 2009 iMac 27" will not boot completely

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