About two months ago, one of the garage door openers in my home’s garage started experiencing an issue where the garage door would stop halfway and wouldn't go up further unless I kept pressing the remote controller. A few days ago, the garage door completely stopped opening beyond the halfway point.

I performed some diagnostics based on the symptoms. The possible reasons for the garage door not opening could be:

1. The motor of the garage door opener is burned out.

2. The garage door opener's track is deformed.

3. The capacitor inside the garage door opener is faulty.
   
   

From the symptoms, I could hear the motor running, but the garage door wasn't moving, which almost ruled out the first possibility.

Upon visual inspection, the track of the garage door opener appeared to be undamaged. Then, I pulled the screw drive carriage down, and the garage door could be manually opened and closed, which also ruled out the second possibility.

Next, I opened the garage door opener motor unit cover and found white powder on the capacitor terminals. This strongly indicated an issue with the capacitor.

To confirm, I unplugged the garage door opener’s power cable and removed the capacitor. I then swapped in a capacitor from another working garage door opener, and the issue was resolved, confirming that the faulty capacitor was the cause of the problem.