If you knew that a smaller model used the same logic board, they MAY be transferable throughout the range - the firmware and parameters are normally stored in a reserved area on the disk - this is not certain though.
Looks like the only choices are:
1. Try to obtain (watch for/advertise for) another failed example, in the hope the logic board is good.
2. RMA it and hope, though my guess is that they'd be able to tell that it didn't die of it's own accord (though I'm not convinced that a reversed connector SHOULD be automatically fatal).
3. Fall on their mercy and hope they can provide a solution at a fair price.
Some people DO appreciate honesty!
I remember a case at my local Tandy (radio shack), where a friend had bought a voice activated variable speed tape recorder (real fancy and expensive) and a mains adapter, and blew it with the wrong voltage or polarity - asked me to look at it, but I was sure the chip would be fried... put aside thoughts of throwing it back under warranty, as I told him it would probably be obvious what had happend.
Asked what it would cost to repair, and related the sad tale, but they said they WOULD put it in as a warranty job, since they also sold the adapter that killed it, and because he admitted an honest mistake.