DIAGNOSIS The light timer setting has been inadvertently changed or disabled, likely via a remote or wall button press sequence.
FIX Reprogram the auto-light duration.
1. Press and hold the light button on the wall control panel for about 10 seconds. The opener light will flash.
2. Immediately after the flash, press the light button again. Each press cycles through the timer options: 1 minute, 5 minutes, 10 minutes, or 'always on' (which is your current problem).
3. Stop pressing when you get to your desired duration. Wait a few seconds; the opener will save the setting with a beep or light flash.
IF THAT DIDN'T WORK control board on the motor unit might have a faulty relay for the light circuit. Try unplugging the opener for 30 seconds to perform a full power cycle reset, which can clear a stuck relay state.
HEADS UP If you leave it in 'always on' mode, the bulb's lifespan will shorten considerably. Consider swapping to an LED bulb if you haven't already—it runs cooler and uses less power if it does get stuck on again.