A reader sent me the following note recently:
"Do you have any idea why our garage door opener would suddenly open and close by itself? Ours started doing that two days ago. It will do it over and over and sometimes it only goes part of the way and stop. Sometimes you can push the button and it will stop it and sometimes and will just keep going up and down until we unplug it. My husband tried cleaning it out and changing the codes and several things. He usually can figure out how to fix something but this one has left us puzzled. Any ideas?"
A garage door opener with a mind of its own can be a real pain. It can also be dangerous and an invitation to uninvited guests. If it happened only around Halloween, well, that would be pretty cool. But aside from that . . . not so cool.
My first suggestion would be to change the code, but you've already tried that. My next thought would be to check for a short in the wiring. If the wires look good, I'd then turn my attention to the buttons, on both the wall and the remote. If they are old, they can start sticking. Both parts should be replaceable.
I have heard tales of malfunctioning circuit boards on old Stanley garage door openers that cause the doors to open by themselves and the lights to flash. I can't suggest how to repair it - it's probably just a simple solder repair -- but it might give you some idea of where to look. A veteran garage door repair person could probably help you out.
Beyond that, I'd offer two pieces of advice:
1. Do a thorough troubleshooting and maintenance check. See Troubleshooting the Most Common Garage Door Opener Problems and Simple Garage Door Maintenance Tips.
2. When all else fails, especially if you have an old unit, a replacement would almost certainly take care of the problem. See 5 Reasons to Replace Your Garage Door Opener.