[CCTECH] AT&T PC7300 / UnixPC is ill! :(

I managed, with a bit of yanking about, to get it disassembled, down to the motherboard, as per the 3b1 FAQ. I got some of the big dust out and reseated all of the seatable chips. There didn't seem to be any major damage anywhere... one of the fans had a cut line which I repaired, but there was no evidence of any type of overheating. Most socketed chips were reseated, everything was powered on once again, and the same thing seems to happen. :( The rectangles appear, the floppy drive sits and spins, and the hard drive spins up and sits there. There is a loud beep/click type sound, which I'd figured to be the heads unparking themselves. When the hard drive cable is removed, the machine freezes at one rectangle, so was thinking it could be something along those lines. Will see if I can dig up a HH ST-506 drive somewhere soon. The power supply looked OK... one very slightly mad looking / bulging cap, but nothing overtly broken. (My DMM is in the mail at the moment, so I wasn't really able to test much. :() The only other thing I think I can report are that the four indicator LEDs are at a constant on state - could also be normal for this part of the boot cycle for this machine, too.