Diagnosis
The auto-light timer feature is disabled or malfunctioning. The light duration is controlled by a setting on the logic board.
How to Fix It
Reset the light timer. Press and hold the light button on the wall console for 10 seconds. You should hear a beep from the motor unit. This resets it to the default (approx. 4.5 minutes).
If That Didn't Work
The logic board's light relay may be stuck 'on'. Unplug the opener for 30 minutes to let the board fully power down and reset. If it's still stuck on after plugging back in, the board needs replacement.
Heads Up
A light that stays on constantly will burn out the bulb prematurely and can generate enough heat to be a concern inside the motor housing.