Very sick imac won't complete boot (not a HD problem)

Question

My imac (24-inch Early 2008) is not completing the boot process. After the apple appears and then the "working" pinwheel has spun for a while, the pinwheel stops and never recovers, forcing me to do a hard shutdown. Below I'll list what i have tried and what was the result.
-- My first thought was that it was the HD. It's always the HD, you know?  Well, I replaced the hard drive and we're still having the same issue. BTW this means my data is fine. the orig HD is no longer in the imac, and was totally readable by my other machine.
-- I've tried booting from an external HD (not the original drive, hooked via firewire and then by USB), a usb thumb drive (once with a Snow Leopard boot, then once with Lion) and of course the install disk. Displays the same behavior for all .
-- Attempted to boot in safe mode (CMD Shift):
          -- --Displays apple screen with the progress bar
          -- --fills the bar about 30%
          -- --bar disappears and is replaced with spinning gear
          -- --gear freezes, no boot
-- pulled and re-set ram in slots (not original RAM, but replaced w Kingston RAM when I got the machine in early 2008, and there have been no probs until now). Tried switching slots, tried each ram card alone in both slots.
-- PRAM Reset: CMD + option + P + R
-- SMC Reset: Unplugged for 15 seconds, plug and wait for 5 seconds, press power
-- Unplug for 15 seconds, hold power button while plugging in, release power button, press power to turn on (Some other variation of reset I found out there, don't remember what they said it was for)
Verbose mode, shows it stopping in roughly the same place no matter what I'm trying. The same place being the initialization of the network cards. Even tho' verbose says it logs to /dev/console/ there is nothing in that directory for whichever boot drive I'm using (yes, I looked in hidden files). So, I hand copied the last few lines from my latest attempt:
yukon: Ethernet address BLAH BLAH
Airport_Brem43xx : Ethernet address BLAH BLAH
IO80211Controller:: dataLinkLayerAttachComplete () adding AppleEFINVRAM notification
Airport: Link Down on en1. Reason 1 (unspecified)
I have had some verbose logs stopping after "yukon: Ethernet address", as well as other lines that all seem to be related to either one of the network cards.
It will go into single user mode, so i imagine the solution has to come from things I can do at that command line.
I've seen some posts listing those lines from error logs, etc., but they all seemed to be issues with slowing and poor performance (which my mac had displayed prior to death). The solutions, if any, don't really apply to me since I can't boot at all.
I've got to get this puppy up and running for the start of school in a week. HELP!  :eek:
Please don't make me go to genius bar!
juliana
P.S.  I should note that the OS is not yet installed on the internal drive. After I replaced the drive, I figured I'd boot off the install disk and install then. Do you think it's worth opening it up again, take out the drive, install OSX from one of my other machines, then reinstall?  It's an imac, so it's a bit involved. But I can't imagine it would be any different than trying to boot from an external, right?

Answer 1

I have one machine (iMac 2006 Late) that had the same problem.  It would not boot from ANY source and all the things I have tried are the same as what you have tried.  Finally, after the computer sat unplugged for a week or so, I ran across the web site linked below.  They had a list of a number of power up key commands.
I do not know if it was conincidental or if it actually cleared the problem but after I did the Command-Shift-K comands twice, I tried my Lion Installer flash drive, which had never been recognized earlier  and lo and behold, it was recognized on an Option Boot.  It then allowed me to actually begin the install from the flash drive.  I won't know till tomorrow if it completed the install but it is more progress than I made in a month of trying before the Command-Shift-K combo.
I had previously scrubbed the hard drive right before the problem started so I do not know if it would have booted from the HD had in not been completely erased.
Give the Command-Shift-K combo a try and let us know if it works or if my machine suddenly for no known reason, decided to rejoin the land of the living.  Like I said I did do that combo twice in a row.  I don't know if it makes a difference but there ain't a heck of a lot to lose if you try it.
http://www.jacsoft.co.nz/Tech_Notes/Mac_Keys.shtml