If the light is flashing rapidly this means you have a stuck button on one of your remote controls. Take the batteries out of each remote control. When you remove the batteries from the bad remote, the light will stop flashing. This remote needs to be replaced. If you have a wireless keypad remove those batteries too.

If you have any remotes from old openers remove the batteries from them also.

I have a Craftsman GDO manufactured in 2005. The wall unit keeps blinking. The remotes are lost, so the wall unit is the only activator. The sensor lights are in sync (green and yellow). I pressed the lock button down for the recommended 5 seconds and it still didn't stop the light from fast blinking. Is the wall unit probably defective? Possibly the lock button circuit? Do these garage door openers only last around 10 years?

I have this exact same problem with Craftsman Garage opener unit on the wall. The wall opener is blinking green continuously. Garage door opens/closes without problem. I don't have any remotes.