By wade shaddy updated december 19 2018 you push the button to close the garage door.
Garage door opener starts then reverses.
If the garage door only travels down an inch or so before reversing something is probably blocking the beam between the two safety sensors at the bottom of the rails or the sensors aren t aligned.
Photo eyes or safety sensors are mounted to the track on either side of the garage door about 6 inches up from the ground.
I have a garage door opener stanley d1000 a07 date 98523 i hit the wall button or remote button and it hums starts to move then stops and reverses itself then stops.
The photo eyes send an infrared beam across the bottom of your garage door opening if that beam is broken the door will reverse.
When the opener is activated the screw rotates causing the nut to move until it reaches the switch.
One for the opening limit and one for the closing limit.
It goes partway down reverses direction and goes back up again.
There may be two nuts on one track.
Reverses on its own.
When the opener reverses the screw turns the opposite way and the nut travels back.
The 2 nd cause is the closing force could be set too light and the normal tension of the closed position exceeds what the door believes to be allowable tension.