Hello OptimAdam, I would like to know which BIOS version you installed on your motherboard. You can try to install the previous BIOS version using the recovery method. Desktop Boards — Instructions for Recovery BIOS Update
Have you tried removing the CMOS battery?
I installed BIOS 0336.
I have tried recovery mode on 0336 and 0319 and both show error 5A on boot.
I have tried removing the CMOS battery and it has made no difference.
Looks like it gets a bit further with 0310. The machine beeps and shows the on-screen options but the keyboard is none responsive, so cant select anything. I have tried different usb ports but its made no difference. There are no PS\2 ports on the board so are unable to test a different interface.
The system still shows 5A in the corner.