A door that refuses to open is usually one of four things. You can narrow it down from the driveway without touching anything dangerous.
1. The opener has no power
Check that the unit is plugged in and the breaker has not tripped. If the motor light is dead, start there — it is the cheapest possible outcome.
2. A spring has broken
Look at the spring above the door. A two-inch gap in the coil means it has failed and the door is now full dead weight. Stop using the opener immediately; forcing it strips the drive gear.
3. A cable has snapped or unwound
A cable hanging slack beside the door, or a door sitting crooked, points at the cable and drum. The load is unbalanced and the door can drop.
4. The opener itself has failed
If the motor runs but nothing moves, the drive gear or carriage is the usual suspect. If it does nothing at all and the power is fine, the board or capacitor may be gone.
What not to do
- Do not adjust, loosen or remove a torsion spring — the stored energy is enough to cause serious injury.
- Do not pull the emergency release cord while the door is raised; it can slam shut.
- Do not keep pressing the button hoping it clears — that is how a repair becomes a replacement.
If you have ruled out power and the door still will not move, call a technician. Diagnosis takes minutes for someone who does it every day.