If without removing the battery; you measure the battery on the Real Time CPU board on the far right by touching the Battery Top and the metal case of the RTCPU board chassis; you will see it is below 3.10 VDC.
The BIOS needs to be reflashed or setup. We do this on a bench with a binary floppy program.
Someone may have pictures for you board # 3-424-xxxxy ???
You would need a power supply, ISA video card, VGA display monitor, PC keyboard to fit the plug on the RTCPU in order to set the BIOS manually.