Diagnosis
The auto-light timer function has been accidentally disabled or the control board's logic for it is stuck.
How to Fix It
This is controlled by a simple button sequence on the wall control panel. 1) Press and hold the square light button on the wall console for about 10 seconds. You'll see the light turn off and then back on. 2) Release the button. This resets the auto-light timer to its default setting (usually about 4-5 minutes). 3) Operate the door to test it. The light should come on with movement and turn off after the delay.
If That Didn't Work
If the light still stays on permanently, there's a small chance the light relay on the main logic board is stuck closed. Try unplugging the opener from power for a full minute to perform a hard reset on all the electronics, then plug it back in and test.
Heads Up
If the hard reset fixes it but the problem comes back, it points to a failing component on the board. The fix then is usually a replacement logic board, which is a more advanced repair.