Changing PSU did not help. A single board that sometimes had 0 chips instantly started hashing, while other two were not hashing like on old PSU but after a single restart it disappeared as well. 0 out of 65 chips read on all boards.

PSU that I put in now was new (ordered from Bitmain) and was tested on working unit, which means that it is not a problem.
Control board cannot be the problem as I have tested it on working unit as well. Data cables I am yet to test but I doubt they are the problem.

I will quote this message in THIS THREAD as that is where it might help people. I will provide pictures of a single hashboard which I think started the chain reaction of all boards going down.