My husband and I each have a set of ego's from differtent suppliers. After having them for about a week without any problems, I took A hit off mine. I released the button but the vapor was still coming out of the cap. ( the light wasn't on) I immediately tried getting the atty off (takes a few extra seconds because of the cone) when I got to the atty it was so hot it blistered my finger. After that my battery no longer worked. The next day my husband wanted to see if the atty still worked and put it on one of his ego's It did the same thing to his. Was this just a coincidence and both batteries where the problem or did the atty somehow fry the batteries.