POD HD500 with firmware level 2.10

My built-in volume pedal (EXP-2) stopped working after I temporily assigned it to control reverb level.  The unit is now outputting 100% volume independent of the pedal position.

I've tried re-assigning the volume pedal EXP-2, and calibrating the pedal per posted instructions - no effect.  Tried the same with EXP-1 - no effect.  I've also tried a factory reset, again no effect.  One post says the pedal can become disconnected from too much pressure, but I don't think this is the case, the problem seemed to follow the assignment to reverb level.

Any help would be greatly appreciated, thanks.