I realize I'm grasping at straws, but perhaps someone can point me in a fruitful direction.

This computer was used as a parts machine for another recently restored Compaq 386s, but I can't help trying to get both computers in working order.

The computer's power supply was checked out with the known-good matching computer, and all is well. Earlier the motherboard LED would only flash (apparently due to a short), and strange voltages were on various rails. Now, after replacing several (but not all) tantalum capacitors, the LED burns steady and normal voltages are present. However, while the LED lights, there is no POST beep, no light at all on the floppies, but again normal voltages are present. Aside from fried ICs, does anyone have any suggestions on where to look?