I was having battery issues with my ATT Lumia 950. I tried soft and hard resets to no avail. Finally, LumiaHelp on twitter suggested Windows Device Recovery Tools to reinstall the OS. It took about 22 minutes for me and my internet connection. Afterward, I restored from backup, updated the phone to the newest build (10.0.10586.29) and like 50 something app updates. My battery went from 100% to 85% for the whole process and only got slightly warm. A vast improvement over what I was experiencing. My phone charges properly (8% to 100% in 45 minutes) and doesn't just get super hot. I went from about 40% to 25% over about 7 hrs while sleeping with glance screen set at 30 sec, Bluetooth and wifi on, a few emails during the night and my alarm set. While this isn't stellar, its a vast improvement over what it was. A few more days of testing should give me better results.