I would like to know how you did to solve the failure, since when updating the FIRMWARE it is not coencted but when changing for an anterior it only connects with two (2) cards and lowers the HASH rate.
Sounds like your PIC error is only on one board. Flashing the April firmware let you ignore that error and continue to mine with the other two boards.
If you want to, you can replace the PIC on the faulty board with one from a spare board if you want to. Bitmain doesn't seem to sell spare PICs. Also, try replacing the ribbon cable to the board giving you the issue.