I'd love to know that too! I've posted to two other threads about this issue. My issue seems to be related to the cellular signal. When it's weak like at my home the S5 will get hot and drain (even after hard reset and in safe mode) with "Android System" as the battery drainer ("system_server" process). At work it's fine. I really need a reliable phone ASAP!!
I finally got my S5 working -- had to go to a Verizon store and they gave me a new battery and did another full reset AFTER the 4.4.4 OS update. That helped a LOT, in addition I disabled every preloaded app I don't actively use and that helped a lot more. I also went to the home-screen settings (hold recent-apps button, then tap "Home screen Settings" and disabled "My Magazine" so it wasn't constantly syncing (what purpose does it have anyway?).
Turned Off / Disabled apps:
A couple apps to avoid -- I use them but they have a significant hit to battery life (1/3 faster drain about) since I loaded them:
The battery lasted forever before that last update, now i have that problem also. After sleeping it's drained. I don't want to go without the apps i use. I bought this phone because it was the best, and now it's the worst. I want to get rid of that update and go back to that great phone it was before.
settings, accounts, check and see if google, samsung account is set to sync every like 2 min. Also check DATA USAGE see if there are some apps using a massive amount of data and check restrict background data. Then should only update constantly over wifi
Thank you for the updated information. Because I can not talk out of terms let me ask you some more questions in hopes that one of them will stump you and I don't have to tell you that you could just maybe have a bad battery or a malfunctioning phone.
Love ya VZW