They are misaligned this is the most likely problem and the most common issue with garage door openers.
Garage door closes and reopens immediately.
If the garage door does not close completely or begins to close and then opens back up again the down limit switch needs.
If you re craftsman chamberlain etc garage door opener is closing and then opening up its likely a common problem related to the stop limit mechanism.
It goes partway down reverses direction and goes back up again.
Your garage door is programmed to travel a certain distance before it closes.
The sensors are dirty wipe lenses with a clean soft cloth.
The solution is usually one or more of the following.
Close the garage door with the opener and watch it closely as it closes.
Fast easy step by step process on how to properly program your garage door travel system.
As these wires short against the housing the electrical impulse causes the door opener to activate.
If the door closes while holding the button pressed you are likely having one of the following issues with your safety sensors.
If it closes before that distance has been traveled it thinks something is wrong and it reopens to help prevent any damage or safety risk.
You push the button to close the garage door.
This is almost always the result of a dirty or obstructed safety feature.
The symptom of this is a garage door that is in constant motion opening fully then immediately descending only to start the same cycle again.
But changes in weather conditions can causes your garage door components to shift or contract.