Hello, I bought a JM4 about a year ago (on ebay). It appeared to be in excellent condition. It worked fine until today when I plugged it in. For some reason the backlight on the lcd screen isn't lighting up and there is no sound coming out of the pedal. Also, in the tuner it is showing no input from my guitar. I've tested all cables and everything seems fine. Nothing else about the pedal is acting strangely. Has anyone else encountered these problems? Advise?