Went ahead and flashed the non-working chip via hot swapping.

The non-working one says it's 12V. Any explanation about this? Does it make any difference as now this chip works fine with the slower board. Faster board will POST but I get the keyboard error or no keyboard present. The leds do light up when powered on twice. There is a little bit of corrosion around the battery but nothing too serious - I've already checked the traces.

Before this board went dead it worked perfectly fine with POD5V83 at 100MHz. Then one time at loading DOS just freezed. Power cycle didn't help - blank screen. Tested the board with different CPU. POD on another motherboard. All dead 🙁 I have no idea what happened. But now it seems the BIOS chip got corrupted, keyboard chip might have gone bad and the POD got fried. I'm guessing the PSU. I used one from an older IBM machine.

kixs wrote:

The non-working one says it's 12V.

It's an older EEPROM or EPROM that needs 12V to program.

I flashed it anyway on the board with 5V chip 🤣 The chip works fine on the board I used to flash it. But on the original there is a "Keyboard not present error". Could the wrongly flashed chip be the culprit?

I have the same board and the same error. Cleaned up heavy corrosion due to leakage, checked traces (not all though). I get keyboard leds that briefly light up and then nothing.
I suspect the controller or too much damage from the corrosion.

My guess is the keyboard controller and it's soldered 🙁

I think it too but it's a big guess to have it repaired. My skills are way too bad for it so I need to send it to someone. I don't even know if these chips are easy to find
I would like to have it working though 😒

Some Flash chips do require 12V for programming (or just erasing). Some are pure 5V devices and have internal voltage pumps. The price for this is usually slower writing though.

The AP43 486 mobo has a jumper to select what voltage the Flash chip needs, perhaps this one has it too? Note, only 5V is required for normal (reading) operation.