Help to repair Agilent infinum 54855DSO oscilloscope power issue

[999masks]

if you guys can give me any suggestions i will appreciate it.

I have Agilent infinum 54855DSO which i accidentally shorted at the ATX connector side that goes to Motherboard, i belive one of the 12V output while it was unpluged from MB.
after that the oscilloscope stopped powering on. Mine has Celestica 5100 power supply with 4 power modules.
The current issue:
if i remove the connector(i think it caries some sensing signals, see below more detail) from power supply that goes to analog power generation board and plug the power cord,
it will power on and boots. At this state I measured all the
voltages  from power supply which looks good. As soon as i
connect that plug (this is not a power cable , I assume some sensig signal) it wont turn on. I
measured the voltages from those wires, basically the power
supply has 4 different power modules. 2x3.3V 1x5V and-12 ,
0, 12V the connector that i was referring, carries the same
voltages as their output at ATX connector (maybe POWER
GOOD signal?) basically from that plug if i remove the pin
that connects to -12,0 +12v =24v (any side) the oscilloscope
will power on and boots. At this state the neither power
button or any button works on the front panel. I am asking
if you can help me to troubleshoot or provide the model
schematic or similar. thanks in advance