Same thing happened to me!! Half way through a rehearsal, the thing just crapped out. I went to switch on and on came the light but no effect, same sound as if stuck in bypass.
Had a look inside but like you, nothing looked out of place.
You say you have had repairs done out of warranty was it expensive?
I had to run out and get a new pog, and upgraded to a pog2 not happy at all. All of the character has been swept out of the new version, I want my massive old pog back.
Jimi