Imac wont boot after power failure.

I can boot in target mode and plug another mac in via firewire and run disk utility, but cannot boot the imac on its own. Anyone know what causes this? I have tried to boot holding down command-r, nothing, don't have install disks as they don't ship with them anymore.

Hello
Try boot in safe mode - Hold on at start-up SHIFT key , at least for one min , see if you ah safe mode start up
Try boot in single user mode - Hold on at start-up CMD-S , see if you have a comande line interface - type exit comande to try boot graphic interface
Try boot Apple Hardware Test - boot with D key
This 2 try need an valid Internet acces ( ethernet cable or wifi enable )
Try boot Recover mode - CMD - R
Try boot Apple Hardware Test - CMD - D
HTH
Pierre

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IMac won't boot after power failure?

My iMac wont boot or respond in any way after I experienced a brief power outage. Now it can't seem to switch on at all even after attempting the different resets I've read on other discussions. Please help with advice on any techniques to fix it otherwise steps I must take to get it repaired. Thanks.

Hello, not much you can do other than try this...
Intel-based Macs: Resetting the System Management Controller (SMC)...
http://support.apple.com/kb/HT3964

How to configure V240 auto-boot after power failure?

Hi!
How to configure automatic boot of V240 machine after power failure? After power gets resored, V240 remains in standby mode and one has to press button on front to power it up. It is not convinient because power failure can occur, for example, at night and the machine is not booted until the first user awakens :)

Uhh... I've found publicly accessible document http://docs.sun.com/source/817-5481-11/variables.html :
Looks like this variable controls auto-power-up behaviour:
sc_powerstatememory
The sc_powerstatememory variable enables you to specify the state of the host server as false (keep the host server off) or true (return the server to the state it was in when the power was removed). This is useful in the event of a power failure, or if you physically move the server to a different location.
For example, if the host server is running when power is lost and the sc_powerstatememory variable is set to false, the host server remains off when power is restored. If the sc_powerstatememory variable is set to true, the host server restarts when the power is restored.
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Imac wont boot after long time without restart

Hi
I've got a two month old new Imac 21,5" with fusion drive 1TB, i had it just before mavericks was launched..
i update to mavericks. All was fine, But i allmost never shut down, or restart the imac.
After some time, I did for a reason i dont remember, had to restart the imac. while booting, it was stuck on the grey screen.. i wasn't able to get it started up, not in safe mode, not after disk repair.. i think i might have tried all the little tricks to get it running again...
luckily i did have a time machine back up...
after installing this back up, everything was fine again..
until 2 weeks later, for some reason i had to reboot again.. and again, it was stuck.. only thing to get the imac working again.. reinstall from time machine back up
after this , it tried rebooting everyday, and the imac kept working..
after a few days, i forgot to reboot for a few days.. and what did you think.. the imac is stuk again.. so while reinstalling the time machine back up. I am writing this. anyone else having this rather strange problem.. if i restart the imac now and then i keeps working.. if i dont after a few days, and i do reboot the imac.. is wont boot anymore..
Any suggestions are welcome
greetings

The long tone is an indication that a firmware update is installing. Do you get a progress bar at the bottom of you screen after letting the power button go?
Have you reset the PRAM? (cmdalt+PR when you restart the machine)
Also repair permissions when the machine is up and running.

Imac wont boot after this last update

I downloaded an update (automatically through software update). After it installed it told me to wait for computer to restart and then hold power button until the long tone, then it should be done. I did that with no problem.
Ever since then though it wont boot regularly. It wither sits at grey screen forever OR gives me the prohibit sign. The only way to get it to work it to hold that power button until the long tone again.
Any idea whats wrong and how i fix it??
Thanks in advance for any help.

The long tone is an indication that a firmware update is installing. Do you get a progress bar at the bottom of you screen after letting the power button go?
Have you reset the PRAM? (cmdalt+PR when you restart the machine)
Also repair permissions when the machine is up and running.

PowerMac won't boot after power failure during install

Hi, sorry if this has been asked. I searched, but I'm not quite sure how to phrase it.
I bought a used PowerMac from craigslist and went to install a newer version of OSX. I had a power failure in the middle of the install and now the computer won't boot up. How do I go back to a fresh re-install and get the computer to boot up?
Much appreciated!

Did you use a retail install DVD? If you used a gray disc from another model Mac, that could be a problem.
Because of the power failure, suggest you reset the PMU. How long was the power Off? You may need to replace the PRAM battery.
Resetting Cuda/PMU on Power Mac G5, Power Mac G4, Power Macintosh G3
http://docs.info.apple.com/article.html?artnum=86760
 Cheers, Tom

IMac won't boot after power failure during 10.5.6 update

Help!
Tried to update last night and at something like 80% install, we had a power cut. iMac won't boot at all now - get to a grey screen which tells me to restart. Don't have a wired keyboard. If I did - what are the steps to get this working again.
I believe I have a good backup, but don't want to risk as all the family photos are on the iMac.
Thanks in advance.

Thanks for the help, but can't even get to a screen where I could type anything! I know I'm being dumb here.

IMac wont boot after file transfer from Windows laptop

Hi folks,
I am looking for some advice if anyone can help?
Sunday evening I transferred asome data off an old knackered Windows laptop via my home network. During the transfer, my 2013 iMac 27" started to really slow down and became unresponsive (i tried to cancel the data transfer and restart). In the end I have to force shut down by holding the power button in. Now, upon reboot of the machine, it won't get passed half way of the progress bar - and I've left it an hour at the most and given up.
I have attempted a verify and repair in Disk Utility, and even though I have managed to Verify Disk and Repair Disk, they took an absolute age to get through - I was chatting to an Apple Customer Care person, and they told me to chat back once it was done, which was probably 20-30mins after I started.
I then went on to Verify Disk Permission, which I left running for around 2 hours until it finished, and then moved onto Repair Disk Permissions, of which I cancelled after about 4 hours worth of it doing not a lot!
When I try and boot, it gets to a stage where the hdd is making a repetitive noise, as if it is stuck in a loop somehow.
I am running Yosemite 10.10.1, and have reset the PRAM to no avail.
I am fearing the worst tbh, but my main concern is the data on the drive - any tips on how to attempt to recover that data - or to fix the drive itself?
Thanks
Andy

The correct way to restart in Safe Mode is when you hear the "Bong" sound hold down and continue to hold down the Shift key until a progress bar appears. Here are Apple's instructions on how to correctly restart in Safe Mode.
I would recommend that you also look over Gray screen appears during startup.

IMac wont boot after displaying a black screen and then switching off

Help! My iMac screen suddenly went black, with a huge purple cursor and then a text box with hugely magnified text appeared momentarily and then disapeared, (the text block was just the standard "You are now connected to ...... " the name of our Network ) after some time and nothing happening I quit using the power off button, when I came back after a short while and powered up again now I cant get past the white screen with the Apple logo and the spinning disc? No start up tone either.

Yes, boot from the install disc and then use Disk Utility to repair the drive:
1. Insert the Mac OS X Install disc that came with your computer, then restart the computer while holding the C key.
2. When your computer finishes starting up from the disc, choose Disk Utility from the Installer menu. (In Mac OS X 10.4 or later, you must select your language first.)
Important: Do not click Continue in the first screen of the Installer. If you do, you must restart from the disc again to access Disk Utility.
3. Click the First Aid tab.
4. Click the disclosure triangle to the left of the hard drive icon to display the names of your hard disk volumes and partitions.
5. Select your Mac OS X volume.
6. Click Repair. Disk Utility checks and repairs the disk.

Imac wont boot after 10.8.5

white screen after update. 2012 imac 27". was originally leopard i think. actually third time the same machine has done this on updates since lion installed. Last two times took full erase and re-install to get started. Boots fine in safe mode. disc utility runs fine although repair permisions shows a ton of itunes issues that wont clear in safe mode. Boot in R mode and they show to clear but show up again after restart. Ready to go Office Space on this thing. nothing connected. add on software is Quickbooks and office only

updates
jan 6 - erased drive, reinstalled 10.6 using disc, update software. gets to 10.8 and white screens on restart. disc utilities agian, repair disc-no errors, repair permission has a few that wont go away
jan 7 - erased drive, reinstalled 10.6 using disc - works great, update software to 10.6.8 - works great, download and install 10.9.1 - white screen, agian with disc utility etc, also tried internet recovery
jan 8 - wiped drive again. downloaded discmaker x and bought new 8gb jump drive. download full version installer 10.9.1. make bootable disc. restart and boot from disc. installs and restarts to finish install. then grey screen
i dont know what else to try here. ive called several local places and left msg's. im currently doing the erase thing again but this time with secure 3x overwrite option.
drive is 1TB ST31000528AS
since 10.9.1 install there are two other drives showing up on disc utility.
disk 2 - OS X Install ESD
disk 3 - OSX X base system

IMac wont boot after update had an error.

My iMac freezes when trying to start up after an error occured when trying to do it's automatic apple software update. Stays on a white screen with time cirlce going round and another circle with a diagonal line thru it. Said it would re-download updates when it had booted back up. but now it will not boot. Is there anything I can do or is it serious?

Start your Mac with the original DVD that came with the computer and run disk utility on your hard drive to repair it. Also repair your permission then restart your iMac normally.

Help! P6N wont boot after power outage.

We had a power outage this morning and after the power was restored I reset my UPS. Now my system is almost dead. The only indications of life are that the HD access light, and the power light flash at a 1 Hz rate. I tried resetting the BIOS (SW3), but no change.
Motherboard: MSI7320 (P6N)
CPU: Intel Q6600
RAM: 4Gb OCZ Platinum

try with a different power supply first.
remove all components...
test a RAM stick by stick a time
left it boot only with minimal processor, a stick of ram and a graphic, maybe if you have.
you can leave not to put your hard disk / optical devices at a moment.

IMac wont boot after change

Well I come from a linux background, so always have a lot of terminals open. Was getting a lot of prefork errors, and after looking all over I found it seemed I was running out of files. I googled around, saw a suggestion and made a change to a system file (not the /etc/sysctl.conf). Somewhere 6 or so levels down. It said you needed to reboot, so this am I did and now I am stuck at a white apple screen with the spinning gear.
I tried safe mode (which I read is just shift on boot). I saw a the same boot sequence except a grey progress bar, but after the bar disapeared, I am in the same spot.
I'm looking for my original install disks, but while I look, is that the correct way for safe mode?
Also, I tried booting off a live linux CD but when I mounted the drive, the .bash_history was not updated since the terminal was closed and not <exited> I guess.
Thanks

The correct way to restart in Safe Mode is when you hear the "Bong" sound hold down and continue to hold down the Shift key until a progress bar appears. Here are Apple's instructions on how to correctly restart in Safe Mode.
I would recommend that you also look over Gray screen appears during startup.

Imac wont boot after update. twice!

I tried to install an update the other night and it finished. I restarted my computer and it ran fine for about 20 minutes. It slowly started to run worse and worse. Finally i restarted and this time the gray apple screen came up with a loading bar. It loaded and then the loading wheel came up and never left. I restarted and it would go to the apple screen with the loading wheel and would not make it past. Today i took it to the apple store and they tried a few things that failed. We ended up re-imaging my computer. I get home tonight it runs fine i try to update and once again the computer crashes on me. Any help?

I would hate for you to have to make another trip to the Apple Store, but if they "reimaged" your iMac, which I assume to mean reinstalled Snow Leopard, then I would probably suggest taking it back to them and have them do whatever they did again and this time followup with doing the update themselves for you in the store. That way they can see the problem firsthand if it recurs or perhaps correct anything you may be doing wrong, not to suggest that it is your fault however.
Regards,
Steve M.
Message was edited by: Steve M.

Trouble booting up after power failure

After power failure(two hours), when booting up imac, just get a grey screen with blinking folder icon containing question mark.
I can hear clicking noise (hard drive?) that goes two or three clicks and then seems to give up.
How do I get it rebooted. Have disconnected and tried again with no result.

Sounds like the power failure may have fatally damaged the HD. Going forward use a UPS to protect your system, power surges can be very damaging to computers. You and try troubleshooting using Apple's Flashing question mark appears when you start your Mac but I think you may find the HD has failed. For confirmation you cal also run Apple Hardware Test in extended mode. Run AHT about 3x back to back and if it reports errors it's time to take the machine in for service.

Imac wont boot after power failure.

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