Was it throwing the checksum error before your issues started?

I believe the bad checksum message means the latest game code that was uploaded to the game is corrupted.

Given that, the game can't run the updated code and has defaulted to running the default version of code on the PRISM. On my game, the default code was really old and was just functional enough to allow the game to be updated. It's been years since I actually played with it.

I would reload the latest RFM game code and see if that fixes your problem. Upadating requires a null modem serial cable and a PC with the P2K updater app.