My last three cmg infinities failed. two were mine, one was a gift (it failed too)-at the time, I assumed that screwing the cap on too tightly was the cause, and that cmg had since fixed this design problem --but, is it still happening? - I don't know if I put the wrong battery end in, since there is no indication on the flashlight which end to insert, and I don't remember..I usually end up using marking pens or scratching pluses or minuses on the barrels to remind me..(hmmwv; take a note :>)