Dot was doa - Primary Arms Classic Series 21mm Micro Reflex Sight with Autolive, 3 MOA Red Dot

Red dot was faulty upon arrival. Took out of box and removed protective back plate, turned on per instructions and dot was visible in window. Once mounted to the pistol slide the dot was gone and could not turn back on. Removed from slide and dot was visible again. Any downward pressure on dot and it would flicker and disappear even without the mounting screws installed. I tried a new battery with the same results.