Garage door opener not working

Hello everybody, I have a garage door opener that is not working. It is 15 years old, and I believe it is called MR-2E. It worked fine until I used it the other day, but about an hour later, it stopped working. I checked the power outlet with a multimeter, and it showed 220V, so the power supply should be fine. On the outside, the opener has four pins: PB, PE, GND, and +24V. I checked the voltage between them, and it showed 0V. (I have the same model in another garage that works fine, and there it shows 24V.) The opener has two PCBs connected by a cable. One of the PCBs has a wire that got disconnected (marked "ANT1" on the top right of the PCB). The pictures are not very clear, but I hope they show what you need. If necessary, I can take more. Can anyone help me diagnose and fix this problem?