I have the same problem on model PEB9159…. You have to take the cover off the unit. There are four screws on the back and one on the right side. There is a screw on the top of the control panel that can only be accessed from inside the unit. Then there’s a whole bunch of wires to disconnect but the panel slides out pretty easily. I would take a picture of the wiring before you disconnect so you can remember how to reconnect. Also pay attention to how the door opener mechanism works before disassembling. It’s a little tricky. Hope this helps.