I had the same thing happen, I had board #2 saying xxxxx then all 0000's.

I rebooted it and bam its gone, i reseated all the cables.
Took out the boards and nothing visbile is damanged or fallen off.

I even tried using a dedicated PSU for the board #2.

This is complete failure on their part, I recall seeing the temps reach 90c on board 2 and i was like wtf