I have Liftmaster 8500 Jackshaft door opener that is only 6 months old. All was well. Yesterday power went out so I pulled the "Release" rope and opened the garage door and closed it. Later in the evening, when the power was back, tried to open the garage door with wired/wireless remote and the lock opens and chain starts but the garage does not open or close. Chain stops after 2/3 seconds.

Opened the front cover of the 8500 and see that the unit is in the manual mode. It has not returned back to normal position where chain would engage and operate the door.What do I do to fix it?

Thanks.