Phone stays WARM/HOT since lollipop upgrade. Battery drains too quick.

earsm

I don't like this upgrade. Wish I could go back to the previous operating system. Along with the other issues listed here, my phone stays quite warm/hot since I did the upgrade. Also, the battery drains very quickly. Any way to go back to the previous system? I switched up to a Samsung because I wasn't happy with the Apple phone, but now it might be time to reconsider.

Snn5

While you cannot roll back to the previous version I think this can be explained.  Sounds like some apps were not optimized correctly when you installed the update.  Some of these apps may stay stuck running, using battery, and running the processor hot.  While a factory reset is the best method, you can try deleting any app you don't have to have and trying each app one by one to determine the cause.

I prefer this:

Plug into charger for the entire process

Charge to 100% and back up and factory reset the phone

(DISABLE google backup and restore of apps and app data)

Install update

Factory reset one more time

Unplug from charger

Set up your phone

Leave phone on until it dies and turns off 1 time

Leave off and recharge to 100%

This is my usual process and I have had no issues.

The reasons for disabling app data is due to the fact that DAVLIK is now ART and the Android Optimization process might not go as planned if you just install the update over the old version.  Also, when you go back to the Play Store to download apps, they will be the correct version this time for this OS.  Also, if contacts will not sync correctly, check your ICE contacts (might have to delete those)...sometimes they prevent a proper sync.