This could very well be an EPROM related issue, it would have been very helpful if you were able to install custom firmware on this type of control board, there is probably a way to get in using SSH or something else, I'd try to contact BrianOS and Vnish folks (AwsomeMiner to ASIC.to) and ask if they have a way to burn their firmware on this weird control board.

Custom firmware ignores that voltage setting stored in the EPROM and can many times fix such issues, if there is no option, you are going to need a pro to fix it, they will probably start by copying the hex from a good board to the bad one.