Ahhh, sorry, been out of touch for a bit, on vacation and such. I see that you had two dead ones, it is most likely the battery. Try them with AC power and see what happens. Also, once those charge indicators go below 50%, they will drain quickly. TIP: Don't fold out the antenna. I did that with my first batch of six and lost a couple due to guests knocking them around. I started leaving them in the fixture and low and behold, no drop outs! Now I always leave them in the fixture, unless I am in a school gym and I have some fixtures on the other side in a safe place. Hope that helps!