It powers on and you can hear sound coming out of it but if you plug in a guitar it doesn't recognize any signal from it, it's not picking up the guitar signal or amplifying it. It just makes a slow repeating echo sound over and over. This sound comes out of the head phone jack as well. The controls on the front are responsive and as you click through the presets you can hear differences in the sound, as if it is still processing. Also it makes a scratchy noise when you turn the master knob. I have tried a hard reset, no luck. I tried opening it up and reseating the connections. All the soldering looks good but I'm sure I wouldn't be able to tell if anything was wrong.Any ideas? Does it sound like something fixable? Has anyone gone through service and have any feedback about how it went?