Check these, in this order
Start with the safety sensors, because they are behind most doors that will not close.
- The sensor lenses. The two small units near the floor on each side of the door. Wipe them with a dry cloth. Dust and cobwebs are enough to block the beam.
- The sensor lights. Each sensor has a small light. Both should be steady. A flickering or dark light means that sensor is out of line or has lost power.
- Sensor alignment. They must face each other exactly. A bumped bracket is the most common cause. Bend it back gently until both lights hold steady.
- Something in the way. A broom handle, a bin, a leaf pile. Anything that crosses the beam or sits under the door will send it back up.
- Sunlight. Low sun shining straight into a sensor can blind it for an hour or so each day. Shading the sensor usually fixes it.
- The lock button. Many wall controls have a lock or vacation switch that disables the remotes. Check it has not been pressed.
When the sensors are fine
If the lights are steady and the door still reverses, the door may be binding in the track or the opener’s close-force and travel settings may have drifted. A door that hits resistance on the way down is designed to reverse, so the opener is doing its job. The fault is whatever it is fighting against.
Look for a bent section of track, a roller that has come out, or a door that sits lower on one side.
When to stop and call
Stop if the door is hanging crooked, if a cable is loose or frayed, or if the door slams when it closes. Those are spring and cable problems, and those parts are under heavy tension.
Holding the wall button down will force most openers to close the door past the sensors. That is fine once to secure the house. It is not a fix.