If the customer’s timer runs down and the unit doesn’t shut off:
Have him unplug the unit and rotate the center grey plastic dial labeled under "mode" from "B" to any other mode.
Then, plug the unit back in and turn the power on and then off.
Unplug the unit again, switch the timer back to mode "B" and then plug it back in.
Have him set the time to 10 seconds and see if the bulbs turn off.