A garage door that will not open may have no opener power, a remote-control issue, a disconnected trolley, or a mechanical failure involving springs, cables, or rollers. If the motor tries to lift but the door barely moves, stop forcing it; a heavy door with a broken spring can be dangerous.
Check whether the opener has power
Try the opener light or wall button and check an accessible plug or breaker from a safe location. If the circuit trips again, stop resetting it.
Separate remote-control trouble from opener trouble
If the wall control works but the remote does not, check the remote battery, vacation lock, and programming. If neither works, the problem is more likely power, control, or the mechanism itself.
Inspect springs and cables from a safe distance
A spring with a visible gap or a loose cable can prevent the door from lifting. Do not touch, tension, or dismantle springs or cables; they store substantial energy and require specialized service.
Do not use the opener to lift an abnormally heavy door
If the door is very heavy or will not stay balanced after disconnecting the opener according to the manual, leave it closed if that can be done safely. The opener is not designed to replace a failed counterbalance system.