What stops a garage door from opening?

Several things can stop a garage door from opening, including power failures, mechanical breakdowns, safety sensor issues, and manual locks that are designed to prevent operation for safety. The most common stop is power loss, as opener unplugged, breaker tripped, or outlet failure cuts power to opener, preventing any movement, so check if opener lights are on. Manual slide lock on door track that is engaged physically stops door from opening and must be disengaged before opener can move door. Broken torsion spring stops door from opening because spring counterbalances weight, and when spring breaks, door becomes too heavy for opener to lift, and opener may hum and stop, requiring professional spring replacement. Safety sensors that are misaligned, dirty, or have loose wiring can stop opener from responding to open command in some models, as sensors must show solid LEDs. Travel limits that are set incorrectly can cause opener to think door is already open and stop. Disconnected trolley due to emergency release cord being pulled disconnects door from opener and stops opener from moving door. Remote issues like dead battery, not programmed, or lock mode engaged on wall console stops remote from opening but wall switch may still work. Door off-track, rollers binding, or cable broken physically stops door. Opener logic board failure, stripped gear, or motor overheating also stops opening. Regular maintenance like cleaning sensors, lubricating rollers, and ensuring gutters above garage are clean to prevent water damage helps prevent stops.