Diagnosis
The opener is in 'lock mode'. This prevents any new remotes or consoles from being programmed. It's a security feature.
How to Fix It
Take the opener out of lock mode. Press and hold the square 'lock' button on your wall console for 2 seconds until the light changes. The learn button LED on the motor unit should now blink when pressed.
If That Didn't Work
The logic board may have a fault. Unplug the opener from power for 60 seconds. Plug it back in. This resets the board. The learn light should now be off. Press it to see if it blinks.
Heads Up
Lock mode does not affect already programmed devices. They will still work. This only blocks new programming attempts.