This happen to me also I was in an excellent coverage area according to Verizon (0-1) bars and I was uploading a pic to dropbox and since it was taking for ever I put
my phone in my pocket.
About 5 min later I felt something really hot on my leg so I checked and it wad my phone and it was hotter dan hot. I pulled bat out to let it cook down and had about 4% left when I started I know I had either 50-60%.
After that it messed my phone up.
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