Not sure what type of switch your rig uses but on mine it is a magnet one that is attached to the screen door.
The first test I would try is to open the door and see if it continues to cycle by itself. If it does, I would locate the switch and cut the wire to see if it stops. Cut the wire so you can splice it back together. If the problem stops, replace the switch.
If the cycling stops when the door is open, see what causes the switch to actuate. If it is magnetic see if the magnet is in a good position so it is very close to the switch it controls when the door is closed. If it is a non-magnetic switch, see what is used to activate the switch and verify it is actually hitting the switch.
It is also possible there is a problem inside the motor. There probably is a sensor/switch in there that tells the motor to shut off when it reaches its set position. If that switch gets weird, the motor may not realize that it has reached its position and just keep running.
If all else fails, an exorcism may be warranted.