SQLSTATE[HY000]: General error: 130 Incorrect file format 'featurecodes'

My guess… Disk failure. Maybe it is a coincidence that all servers started failing at the same time, but mysql file corruption would point to that. Can you check SMART statistics on the disk?
It could also be related to RAM failure, but given that featurecodes is a table that is not modified frequently, or even at all, my guess would be disk failure.
If you are performing regular database backups, you could try a database recovery, at least to be able to start FreePBX and then decide how to move on from there.