The only time I experience rapid battery drain and the phone getting hot is if I am inside a building that causes very poor reception. In an area/building with poor coverage will cause the phone to constantly search for a better signal, especially if it has dropped to 1xRTT mode. I have in some cases just disabled data until I am back outside or in an area where the phone can find an LTE signal. This saved battery and cooled the phone down. I had this happen just the other day in the movie theater. Unfortunately, this is a problem with pretty much any phone.