Garage door opens after a power surge.

Power surges love logic boards. You should remove the boards and check for burnt or missing traces on the printed circuit. Especially around the small transformer.

If all else works, I'd start at the limit switch.

You will need to get a surge protector on this unit first of all. You will have to replace the logic board and maybe the wall button or sensors depending on how bad the surge was. Any time the power goes out the logic board can be affected by it. Thanks BB

More than likely you have received a power surge and will need to replace the logic board before it will work. You can run it by hand by pulling the red cord until it is fixed. You can get replacement parts at searspartsdirect.com. Thanks BB

Anytime a door opens and/or closes by itself I look for a smashed wire between the motor unit and the wall button.

If the wire is smashed the insulation becomes so thin that power will leak thru the insulation and activate the door.

Loosen the staples with a small screwdriver and slide the wire about ½ inch to move any areas of thin insulation away from the staples.

The second thing would be a bad wall button or a remote with a sticking button.
Or a remote in someone’s purse that gets the button pushed by other stuff in the purse.

The test is to disconnect the push button wires at the power unit. If the self operation stops you have located the problem. If you reconnect the wires and disconnect the wire at the wall button this will tell you if the problem is the wire or the button.

HOPE THIS HELPS

Replace the logic board. I have seen this problem in the field. More often than not it's due to power surge or lightning strike.

logic board cooked, replace board or entire unit. use a surge protector. homwowners insurance covers damage.

Check the light beam safety at the door's bottom, to see if something is getting in the line of sight.

Thats one of the symptoms of a lightning strike or a power surge. Without actually being there I would suggest replacing the back-board. But as with lightning strikes and power surges sometimes other electronic components could have been damaged as well.

Your opener has been hit by lightning or power surge.
If it's not too old you can replace the 'back board' (the computer board on the back of the opener.) Also If the opener has safety sensors one or both of them may be burnt out too, and if it was really bad then the rpm sensor will go too. So you could be looking at paying half the cost to repair or just get a new opener. Up to you, and get a surge protector. Lift master has a good line of products and makes thier own surge protectors for thier products.