I have the same problem. Looked inside, Everything looks good to me, no loose wires. At the same time, I am not good with this sort of stuff (Soldering, electrical schematics, Etc…) I have a power adapter and it does not work. I try using a battery, still does not work. I just bought it from a dude on craigslist for 30 bux, not a huge loss, but It would be awesome to get this thing working. So to be clear, When the switch is off, I can hear my guitar, turn the switch on the led light comes on, no sound at all. Took a closer look and one of the grounds from the power for the plug was loose. it was on the same peice of solder (i dont know what its called) as a red wire. I soldered it back and it works fine. hopefully that can help some people. IF the pedal is not working when you switch it on, look around for loose wires on the power source (9v plug or for battery )