Home Repair might be a better forum in which to ask this.

Are you close to neighbors? My first guess would be that someone else in the neighborhood has a remote that triggers your opener. And your remote triggers theirs ... so every time you close your door, it opens theirs, and when they notice this, they close theirs ... which opens yours, etc.

I think most remotes have at least two channels they can operate on. You might try changing to a different channel, and hope another neighbor isn't using that one.

Make sure the circuit is well-grounded.

Really strange things happen when electronic devices aren't properly grounded - you get "ground loops" and "floating grounds" and they decide buttons have been pushed that have not been pushed.

Run a single copper ground wire from ground on the opener to the closest cold water COPPER pipe.

And ... it can be a nuisance in old houses where some idiot put 3-prong outlets on ungrounded circuits.

It's NOT GROUNDED!

I agree with the possibility of a neighbor having the same frequency/remote control code. I would have a garage repair person out and let them sort it out.
Lafdr

This happens all the time. Neighbors.

Isn't there a shutoff button/switch for the remote? MIne has one right next to the wall switch. If so, you could turn that off and that'd pin down if it's an external signal or internal problem.