This is a common problem with this unit. I just got mine fixed this week. From my internet research I found that the problem is a design flaw with the on off switch. The button you push is not a switch, it pushes a lever shaped like a tiny golf club. The "club Face" contacts the actual switch. Apparently it is possible to push too hard and dislodge the contact. The repair involved removing the back, taking out the mother board to access the switch, positioning the contact properly and reinforcing it so this won't happen again. It was more than I wanted to try so I managed to find someone to do it for me, he charged $49.00 and it now works perfectly.