Diagnosis
The light timer setting has been changed, likely by holding the light button too long. The default is 4.5 minutes.
How to Fix It
Press and release the light button on the wall console. The light turns on. Now press and hold the same light button. You will see the light flash once after 10 seconds. Release. Each flash adds 30 seconds to the timer. Keep holding for more flashes. One flash is 30 seconds, ten flashes is 5 minutes. To set it back to factory, hold until you see 9 flashes (4.5 minutes).
If That Didn't Work
The light control relay inside the motor unit may be stuck closed. This requires a main logic board replacement, part # 41A4283.
Heads Up
The light timer runs from the last motor operation, not from when the light turned on. Moving the door resets the countdown.