Has anybody had an issue where an entire board just disappears from the miner status page?  Not just a few chips marked inactive or bad, the whole board 2 line is missing.  If so, were you able to resolve it without a warranty claim?

I have tried everything I can think of to get it working again but nothing has done any good.

I've got it running on a 2400w server PSU, so power isn't an issue.  All the PCIe cables have been tested on other hashing boards so I know the power cables are good that the missing board is using, and i've switched out the control board connectors as well thinking one wire might have been knicked or something causing it not to detect.  No change.  Also tried flashing the control board software by SD Card back to the Jan 2017 firmware, still no change.  All connections seem solid, and the board doesn't have any evident damage to it such as blown caps or bad soldering.

I'm out of ideas that could have caused it, but it's really weird given that it's only been online for a week and it was working at 504Mh/s until it just stopped working yesterday or today.

I  REALLY don't want to have to send the entire miner back to bitmain, even to bitmain here in the US, because it will be a huge profit loss for all 4 boards to go offline for 4-6 weeks.