Welder won't weld

[Kuria]

  hello I'm new here and very much a bigginer to posting
My welder a 200p ac\dc pulse won't weld.
It switches on but the OC light is always on and the whole thing is blocked.
I have tested the mosfets good, thermalfuse good, disconnected inverter board output, tested all mosfets on low pressure circuit board, disconnected everything connected to low pressure cb and the warning light just won't switch off. It seems I don't have any pulse sending to the inverter board which btw receives 380 , I tested all diods good, Schottky diods good, silicon diods good, even replaced a 16 pin chip and cleaned the boards with board cleaner i trouble shooted with the repair service I bought it from nothing.
Has anyone else had this problem? I'm posting photo s of the machine and boards.
What the hell controls that protection mechanism? Thank you