Chosen Solution
If the original SSD isn’t recognized by the system either then my next step would be looking into the functionality of the M.2 socket itself. If the socket is bad, that would likely mean a full logic board replacement which is probably more expensive than the repair is worth.
Ouch! Your logic board is the root issue! Leave the Apple SSD in your system and visit an Apple Store as I’m suspecting your system should be covered under the extended warranty program. If they won’t cover it, sadly, you’ll need a new logic board.
