HP 54540C Oscilloscope, SOFTWARE ERROR - PLEASE RECORD THESE NUMBERS

[Wayne916]

HP 54540C Oscilloscope, up to a week ago the scope was working and calibration completed with no errors, while testing an input signal i pressed the "Auto-Scale button" after a few clicks the scope locked up, and now will only show the below Error code, I have tried googling the error code unfortunately i could not find any reference.

"SOFTWARE ERROR - PLEASE RECORD THESE NUMBERS  9A8E 00102008 00FF"

Following the service manual, I have checked the power supply module voltages both in circuit and with a 2 ohm load. All voltages found to be correct.
I have replaced the bios 3.0v  battery and installed the ROM and SYSTEM files from a  1.44 MByte floppy disk. Tried the two versions available, Unreleased software rev T2.26 and Released software rev 2.00.
Both installed OK, but i still get the above Software error code.
The mother board is 98% surface mount components, i have checked the caps for leakage and can see no signs of burnt tracks, removed and cleaned the ADC hybrid modules.

HP54540C serial number US35480103
internal psu = 0950-2369

Any help would be appreciated.