Can't boot G5 even from OS install disk. Help?

Question

I've trolled the message boards 25 pages deep and searched all the "Can't boot my G5" threads and still haven't found anyone describing what my machine is doing so thought I'd start a new thread in the hopes someone can help me out.
Ok I have a G5 dual processor machine. (Power PC chip, not Intel) Things went bad when I tried to do an Archive and Install of Leopard (OS 10.5) The install looked as normal until I got to one minute left on the install. At that point the install never progressed. I thought maybe it was doing some behind the scenes processing and decided to leave it over night. The next day my machine was still hung on that One minute left. So obviously it was a failure. Of course now the problem is I have an install that never completed of the OS and so that partition is, I assume, unbootable. Wiped away the Tiger OS and did a 99% install of Leopard. So I had to shut down by holding the power button.
I think to myself, "No worries I can just boot from my 2nd partition holding down the Option key to select it on the boot up screen". I always keep a partition with an OS on it for times like these. So I reboot, hold option key, select my other partition, things look OK. I get the grey screen with the Apple logo and I get the wheel animation turning. (Not beachball of death but the typical circular, almost sun ray configuration thing) At this point, usually the screen will go black for a moment before the desktop loads. However, in my case once the screen goes black after the load screen, it stays black. Now let me say the monitor does NOT turn off. There is a definite difference when I manually turn the monitor off. When off it's truly black. But this is like a power on black, not true black. (If you need me to explain this better feel free to ask me to clarify)
So the untouched, pristine Tiger partition boot is a No Go. I figured I'd then give up on trying to put Leopard on my desktop machine (I use it on my laptop) and reinstall the original OS and system software from the system disk that came with my G5. I boot machine holding down eject button, place the disk in, close the drive door and shut down again by holding power button. Reboot holding C key and the same routine happens with booting from the disk. Gray Apple logo screen, sun ray circle moving, screen goes black on the attempted transition to desktop .. but stays black. I also tried booting with my Disk Warrior disk to no avail. Same thing happens. (Also tried booting from disks by selecting them manually from booting with Option key down) At first I wondered if it was a monitor issue. That maybe my desktop was up but there was an issue with the signal being passed to the monitor on the resolution jump. Thought perhaps hitting the Eject key on the keyboard when I had attempted to boot from the partition (not from disk on this test) would tell me if it was a monitor issue. If it was a monitor issue, the disk tray should open. But alas, no.
So since I cannot boot normally from any partition or disk I decided to boot into single-user mode.
I did the fsck -fy thing and it told me everything was ok. I had also previously installed applejack and I ran that and short of correcting a few permissions and dumping some unneeded caches it came back with a system OK.
At my wits end I booted into target disk mode and ran Disk Warrior on both the original half installed OS partition and the back up emergency boot up partition from my laptop. Again, everything OK. Hoped against hope that I could actually install an OS onto my G5 from my laptop but I was only given the option of being able to do it from my laptop with the Leopard disk and it would only allow me to do it if I used Disk Utility to completely format that drive first. No, thanks.
Re-attempt to boot G5. Failure. So now I turn to hardware. Disconnected everything beside the keyboard and mouse. Try again. Fail. Pulled a couple sticks of Crucial memory out of the machine and left the stock RAM. No dice. Pressed the small power unit reset button under the RAM slots. No change. Zapped the PRAM. Still nothing. Try to boot in Safe mode holding down shift key. Doesn't work.
It seems to me if I can't even get the machine to boot from the Install disk that there is something going on that is much more major than software issues.
Bad motherboard? Any ideas? Because I'm all out of ideas.

Answer 1

Brother, Sound74, I thought I was the only one pulling the hair out of my chest one by one the past two days. Your situation is very similar to mine, and I'm just as clueless as you are. I started getting kernel panic screens, then nothing on boot, until finally I brought it to the local genius bar. They ran all the usual software/hardware tests, updated Tiger to 10.4.11, recommended I buy Leopard and do an erase-install. My computer, of course, was working absolutely fine by this point. I bought Leopard, came home, backed everything up, then tried to install the new OS. Like in your case, it just up and quit half-way through. Screen went black and a "No DVI Signal" message came on my display (it does this when I turn it on without first turning on the computer).
So I thought, well, maybe it takes a really long time to erase-install, and the monitor is just waiting for things to kick back in. I've always upgrade-installed before, so I couldn't tell if this was normal or not. But about half an hour later, my fans kicked in so fast I thought I had a P-51 Mustang taking off in my studio. I waited a bit more and finally force-shut-down my system. Not knowing what to expect, I nervously tried to re-boot.
Nothing. Zip. I can't safe boot, I can't boot from the installer disc, etc. The only thing I can do is the option-key thing whereby you choose the startup disc. And of course, it only gives the Leopard install disc as an option, because now the entire HD has been erased! But when I choose the Leopard disc, of course it doesn't work.
So I have a nice $3000 paperweight sitting in my studio. I guess I'll have to bring it back to the Mac store, where if it costs more than $300 to fix, I'm going to say screw it and put that dough toward a new iMac.
Sorry I couldn't provide any helpful info, but I just wanted you to know you're not alone in suffering the slings and arrows of outrageous technology.
Keep me posted on any solutions you discover, and I'll do the same.
Noochy1
PS My applecare expired a month ago! AAAAARRRRGGGHHHH!!! **** Murphy and his stupid laws.