My garage door opener stopped working. After experimenting a bit, I discovered that it worked only when a remote was VERY near (e.g. within 6 inches of the antenna).
I replaced the battery, tried a different remote, power-cycled the opener. No joy.
But then one day, I happened to press a button on the remote when it was inside my house, at the other end from the garage, and the door opened. Very strange.
I checked Google, and there are plenty of people with the problem, and they tend to blame RF (radio) interference or a disconnected antenna wire.
I got up on a ladder, to inspect the antenna connection to the logic board. To open the cover, I had to remove the light bulb. The LED bulb. The RF noisy LED bulb.
The new LED bulb was the source of the problem. I didn’t notice it right away because the opener worked so long as the light was off.

Before you replace your Craftsman/Chaimberlain garage door opener because the remotes stopped working, try unscrewing the LED light bulbs.