Turn off Fast Boot in settings. Power off phone.
Plug phone into HTC charger and charge for two minutes or more
While charging, hold down volume up+volume down+power button and continue holding
Phone will turn on and off repeatedly every 15 seconds or so while continuing to hold all three buttons
Keep this going for 2 minutes, then release buttons when phone is ON
Now, let phone charge fully normally (with phone either on or off--doesn't matter) and battery level reporting, charging and battery life should be normalized.
Do this every month or so to keep power system healthy--even if everything seems fine. Also, don't leave phone on charger overnight for best long term battery life (according to HTC tech support: "The first thing they tell us." This is true even though charging is supposed to turn off when battery is at 100%)
NOTE: Another potential fix for battery/charging abnormalities if this procedure fails (esp. after an OTA update when corrupted files can remain stuck in device cache partition)--clear cache partition using this method: http://forums.androidcentral.com/ver...ted-phone.html