Been quite a while, but the old ITT 286 motherboard is acting up again: it has always had this behaviour in which every now and again, the board would have no video on powerup and the speaker will make 7 short beeps. In the past, restarting a few times would remedy this and all would be fine again once booted. Just recently, after having not used the PC for a bit, this behaviour has become constant. The PC no longer displays video, I have tried across multiple video adaptors and monitors, both EGA and VGA to no avail. Upon boot, there is about a 50/50 chance it will either give a single short beep as though it booted OK or it will give the aforementioned seven short beeps. I have an ISA debug readout card and it displays as follows:
-0055 when the system gave a single beep and booted
-0655 when the system gives the seven beeps
In both of these cases, the keyboard lock lights do not work and the video adaptor shows no sign of life.

I have inspected the board and found no obvious damage, the CMOS battery had leaked a while ago, corroded some traces and thruholes around some discrete components and simple logic chips. Some bodge repairs were done to clean up and fix that, but it had been working with said repairs for about two years until now and there is no sign that corrosion or damage in that area has continued.

Does anybody have a reference for what the seven short beeps or the 0655/0055 code may mean on the ITT system or AT compatible boards? Any ideas of where I should start looking to troubleshoot this issue?

Yes, this is the same motherboard with a broken floppy controller that I posted about a while back, maybe it is somehow related or this board is just crappy and unreliable.