The light on the motor on the ceiling flashes a few times. Most likely, it’s a Sensor problem (Liftmaster machines only).
Scenario 1: The door goes down (But not all the way and comes back up!)
Towards the bottom of the two vertical tracks there are 2 separate sensors with photo eyes facing each other maintaining a beam across while the door is coming down. If this beam gets interrupted for whatever reason, the motor assumes there is an object in the doorway so the door goes back.
Commonly this beam gets thrown out of alignment when it gets moved/pushed accidentally, and can be fixed by adjusting it finely (moving it gently by hand until you get the green and the orange lights solid and steady again. Both lights must be ON, must be solid and bright with no flicker or blink and that is when you know the sensors are aligned now.
Scenario 2: The sensors are perfectly aligned and you are still having the same problem. As the door is coming down, the track gets pushed outward and throws the beam out of alignment at a very specific spot along either vertical track due to a mild bump, weak structure or just a loose jam bracket. Framing around the door (garage structure) and all the tracks hardware need to be checked and reinforced.