Boss SD-1 with Monte Allums mod won't put out any signal, even when bypassed.

Hey guys. A friend of mine asked me to take a look at his SD-1 that has a Monte Allums mod (he bought it used and already modded, and doesn't know what the actual mod done to it is). It started sputtering when in the chain and eventually just cut out completely. I took a look and found that one of the capacitors in the output circuit was completely disconnected from the board, so I resoldered it and tried playing through it isolated, but it still didn't work. If anyone has any ideas on what may be happening, I would really appreciate the help!