I did confirm the RCA cable is good, and I connected the driver directly to my amp's stereo right cable to confirm the driver is functioning.

I'm shipping the back panel to Outlaw for repair. The responded to my support request first thing this morning. It sounds like it won't be a problem for them, and they estimate $75 plus shipping. I was hopeful the sub could be retrofitted with updated boards from more recent models, but Outlaw says that's not feasible. Oh well. I'm happy with the LFM-1 and at 80 bucks it's a no-brainer repair.