Just for grins and giggles... did you attempt to install a lockup switch to see if the problem really is the pcm, or farther down the line? That would be a good place to diagnose. .
as for the pcm failing like that, I havent heard of it but I guess its possible. I just installed a relay-type mystery switch with a momentary on the other end, and man does it work niiiice...
good luck
-j