Have you done a system cache clear since the update? It will not affect any of your data or settings, but may clear the battery issue.
Directions if you need them:
Power down phone
Hold volume up/down & power simultaneously until you see the Boot Mode Selection Menu
Use volume down to navigate to 'Recovery', use volume up to select
Should see screen with triangle and exclamation point next to an Android
Press volume up/down simultaneously to go into system recovery
Use volume rocker to navigate to 'wipe cache' and use power button to select
Once finished, use volume rocker to navigate to 'reboot system now' and use power button to select
