If it is stuck in the open position you will most likely find the trolley is jammed against the bolt just in front of the motor unit. You will need to loosen the chain enough to release the tension and then run the opener until the door closes. While the door is closed locate the 'up limit' on the side of the motor unit and turn this control 2 full turns in the opposite direction of the arrow printed on the cover. Tighten the chain.

Ok I tried that but there is no chain on this model (model no. 139.53491), just small plastic gears. The inner trolley is stuck in the open position though. Any other ideas? thanks again.

Sorry you have the screw drive opener. The fact the lights come on when you press your remote shows the receiver is working but the information is not getting to the motor. I would remove the logic board and check for burnt or missing traces on the printed circuit. The only other option would be to replace the logic board.

Ah ha. I will look into that. Thank you sir.