I recapped my Beta Lead and am now having some problems with it. After putting it back together I plugged into channel A. It sounded great for a few seconds and then there was a loud thump/pop sound. The channel LED went out and the amp stopped passing guitar signal, now just putting out a loud hum (which can't be controlled by any of the knobs). I shut the amp off immediately and opened it back up. Everything looked ok, nothing burnt and the fuses weren't blown, so I tried again.
Channel A worked great, and I played through it for a few minutes with no problem. Channel B worked but had a lot less gain at the exact same EQ/drive settings. I plugged into the Both input and I got the loud pop/hum again, no LEDs lighting up, and no guitar signal passing. Went back to the individual channels and I'm getting the same result. Any clues what could be wrong?