That's a tough question to answer. It requires completely disassembling the unit, unplugging pretty much all of the plugs and removing the circuit boards. I had to locate the problem, test the transisters, and then mod the board. The problem is a bad design by the manufacturer. What causes it to fail will do it again. The board gets too hot and the transisters fail over time. I decided to install a few mini 5v fans to blow over the board to ensure it stays cool.