Mean Well RST-10000 10kW 24V power supply without function

[BUAROD]

I started this topic in "Other Equipment & Products" and changed to "Repair" now! I will explain the reason.

After removing the top cover it seemed to be an easy job to change the output voltage from 24 V to 48 V:
this 10 kW version is a parallel connection of two 5 kW units (picture 1).
Mean Well allows up to 4 x RST-5000 to be connected in parallel (picture 2 and 3)
to get up to ~20 kW of output power! Same you can do with connecting 2 X RST-10000 in parallel.
My idea was to switch the two subassemblies in series to increase the output voltage to my desired 48 V.
The idea failed with the result, that even after changing back to the original wiring the output is dead!

Conclusion (as allready written in "Other Equipment & Products"):
I think it is rather unlikely that components were damaged during the procedure.
What I tend to believe: the "irregular operating condition" was stored as fatal error in the memory, forcing the system to a permanent shut down now!
The PIC18F46K80 has a 1 kBit EEPROM inside ...

Any helpful ideas how to procede without circuit diagrams and knowledge of the PIC`s software?
PS: the communication between the two PICs is still active, but it looks different on the oszilloscope now ...   

Update Oct. 26, 2021:
after checking several components I found two defective opto couplers. They enable remote switching of the output.
The input circuitry of the RST-10000 PCB seems to be different to the regular RST-5000 PCB: with identical external
wiring the LEDs inside the opto couplers were damaged. After changing the couplers the power supply works again!