My similar back-story (feel free to skip to my answer below):
I have a Genie 3055, a wall button, a wall keypad outside, and a G3T Three-Button Remote for each of 2 cars.
This morning, one remote had trouble when I was leaving: the middle button (which I usually use) didn't work, and I needed to press a different button to get the garage door to close. (Yes, I'd programmed multiple buttons to open the same garage door just so that I could press any button and expect my door to open.)
Then when I returned home and tried to open the garage door, none of the remote buttons worked. I needed to get out of the car and use the keypad.
Even trying 3 new batteries (2 of which were from unopened Duracell and Energizer packages) and even trying the known-working battery from my other remote didn't work in this remote controller. So it seems like the remote itself was suddenly broken (which would be weird).
"[If] Garage door opener works from the wall control, but NOT from the remote [then:]
- Check all remotes (if all the remotes and wireless devices stopped working at the same time, this could indicate the circuit board needs replaced)
- Replace the remote battery if necessary
- Reprogram the remote to the power head
- Replace the Genie remote if needed"
So I even tried re-pairing the remote (with its new battery installed) to the motor. But the remote's LED lights never turned on for any button press.
What worked for me:
https://youtu.be/u9dXZKoAz0I?t=111 said to try cleaning the metal contacts (where battery gets installed) with q-tips dipped in alcohol and gently try to bend them in to create a tighter fit. I doubted this would help because it already looked clean and tight.
But I bought some Equate 91% Isopropyl Alcohol and used it as instructed by that YouTube video, and immediately the remote started working again!