I recently picked up a couple of Armattan quads that are a few years old and originally flashed with Cleanflight.   Being the tinkerer I am, I ripped out the DSMX receiver and put in an ELRS all while deciding to flash the FW on the board and updating the ESC firmware to Bluejay.    

I managed to get about half a pack in before crashing down and finding that motor 4 is no longer spinning.    I swapped motors to see if that was the issue (all are functional).   All 4 ESCs can be read and flashed (and reflashed) and I also learned that if you flash the wrong FC firmware it wont always see your ESCs. 

I know that the board is  an (older) HGLRC stack and was flashed (and reflashed) with OMNIBUSF4.   
Is it possible that the ESC for M4 just pooped or might this be a configuration issue that I am missing (due to hastily upgrading just because)?

FC and ESC firmware basically tells the firmware the board layout in terms of pins/pads and component placement but having said that it may contribute to issues with the board due to gyro alignment or uart issues. If you managed to take off then this was not a direct cause.

Usually during a crash the motor may stop due to the impact which may cause a huge current surge or voltage spike that may cause the ESC to fail. This is why disarming at the right moment is important to avoid serious damage.