Just received this light and it wouldn’t work. Removed the clip and it worked. There is a cutout in the rear of the battery tube, just below the threads that the clip rests in, the clip has a protrusion that rests on the cutout. On my light, when the clip protrusion is not in the cutout, the light is locked out and will not work. If the power button is at 12:00, the cutouts for the clip are at 9:00 and 3:00.