Diagnosis
This points to a failed internal power supply board or a blown thermal fuse. A power surge or repeated overload (like a very heavy/binding door) is the usual cause.
How to Fix It
Check and potentially replace the thermal fuse on the logic board.
- Unplug the opener from power.
- Remove the light lens cover on the motor unit to access the logic board.
- Locate the small, white thermal fuse (usually near the power input wires). Test it for continuity with a multimeter. If it shows no continuity, it's blown.
- Replace it with an identical-rated thermal fuse (commonly 130°C).
If That Didn't Work
The main power board or capacitor has likely failed. This requires board-level repair or replacement of the entire motor unit, which is a professional job.
Heads Up
Before replacing the fuse, you must diagnose and fix the root cause. If your door is heavy, unbalanced, or binding, it will overload the motor again and blow the new fuse. Have a professional inspect the door's balance and springs first.