How to get this 2004 PMG5 back up and running?

Question

Hello all,
My girlfriend and I picked up a bunch of Power Macs the other day: 1x G5 Quad, 1x G5 2004 Dual 1.8 and a G4 MDD 2003. The G4 works great and I upgraded the graphics to a lovely Geforce 3 Ti200 card. Great OS9 machine!
The G5s though, are a different story. The Quad has the infamous Delphi LCS, which broke. The logic board is undamaged, but the previous owner was not kind to this machine. The red LED near the top RAM slot shows the ill fate of this machine.
My question is mainly about the 2004 Dual 1.8Ghz machine. It POSTs fine, but once it tries to boot from a disk or a DVD, it hangs at the Apple logo. No spinning wheel, just an immediate freeze. The fans go turbo as soon as the open firmware is loaded.
Specifications:
G5 Dual 1.8Ghz from 2004
2GB PC3200 (2x 1GB, tested as working properly in other machines)
Radeon 9600XT
Disks tested include several SATA drives as well as a Kingston HyperX SSD. DVDs include 10.4.6 Tiger and 10.5.6 Leopard, universal versions.
What have we tried so far:
- PRAM reset (machine doesn't respond to the command, just continues it's boot attempt)
- Safe mode / single user mode / verbose mode (again, machine does not respond to the commands)
- Replacing the PRAM battery
- Booting into Open Firmware (works fine, the multiboot section works fine as well, and the install DVDs are detected)
- dev /memory .properties command in Open Firmware (shows SPI data as expected, RAM appears functional)
-  PCI SATA card to rule out a defective SATA controller.
What we haven't tried yet:
- Apple Hardware Test to diagnose any remaining problems.
So, dear Apple community, is there something else we're missing here? I can get a Dual 2Ghz logic board + CPUs on the cheap if need be, but I'd rather get this one back up and running.

Answer 1

I am delighted that you are someone who practices the reuse and recycle idea. Up until yesterday, I did not know that a Power PC version of the Mac was even made. I had been using a Intel imac that I bought new in 2007, and the shop that I had it at said that it would be too expensive to fix - so they were willing to let me have this power pc G5 for what I had put down for the repair. It looks like this PPC G5 is just about new - and I suspect because it was made non-upgradable from almost the git go.
I am wondering if you have found anything that will adapt your machine to newer operating systems? I am wondering if you have tried an external hard drive possibly?
If you are familiar with the Meet Up network - I am a member of the Okanagan Mac Users Meet Up group. I was thinking that it might make a lot of sense to make a proposal to Apple that the outfits that are making counterfeit software should be given an alternative that would be legit. I am thinking that these rogue software developers could be invited to make a budget line of adaptive software that could make use of the power pc hardware - and could be linked with some kind of software that would be able to interact with the advanced platforms. I would like to be able to get my system to run Chrome and Google docs. I also need to connect my HP Officejet 7610 wide printer.
Anything you care to respond about is gratefully received,
Alan Blanes
Kelowna