If that LED is flashing rapidly it means the opener is receiving a signal. Take every remote you have and remove the batteries. Make sure you don't have an old one stored somewhere that could have something pressing against the button. If you have added anything new to the garage or house that plugs into the wall, unplug it and check the opener. I would do each of these things one at a time and check the opener.

What was the original symptom you had other than the light flashing?

Thanks, Don. It must have been one of those old remotes that was stored in a drawer in the garage. I removed the batteries and tossed them and that did the trick. I was then able to re-program the remotes and my Home Link.

This forum is great.

When I press the code into the wall mount outside the garage, it starts to blink and the garage door will not open. when I press the wall mount inside the garage it works just fine. can you please advise

wall switch of garage door opener will not stop flickering.
It opens and closes door fine.I replaced switch,but it did
not solved the problem.

Petieboy... your solution worked for me on my LiftMaster! Thanks!