Roberto was very courteous and explained the details of what he was doing. He also pointed out a repair I might consider having done (replacement of the bottom panel of my door) and asked the office to follow up with me on this. Someone did follow up with me and since replacement of the bottom panel is not an option and I would have to replace the door, I decided that I can wait.
The power to your garage is out with the door shut, and you need to get your car out or you'll have to take a bus. You'll notice a cord—usually with a red handle—dangling down from the guide track that the opener uses to open and close the door. This is the manual override. Once pulled, it allows you to open and close the door with your own power in the form a little elbow grease.