So I have updated my unrooted Note 2 to version 4.1.2 and below describes what happened:
1. Battery drain very fast, can't even last 24 hours. The battery details show "Android System" chugging all my battery juices.
2. On 2nd day, I tried "Factory reset" on Settings menu but still my battery drains very fast by "Android System".
3. On 4th day, I installed Kies on my PC and did the "Firmware Upgrade and Initialization". Noticed an improvement in battery life but after 4 hours, I noticed "Android OS" is now taking his turn to chug all my battery juices.
4. On 5th day, woke up and noticed battery drained >20% by "Android OS".
5. 6th day (today), I did another "Firmware Upgrade and Initialization" on Kies and now I noticed "Android System" took over and took over >29% battery usage in under 1 hour.
6. Now, I am running "Firmware Upgrade and Initilization" for the 3rd time and is hoping for the best.
Should I root my device and downgrade to 4.1.1? Before update to 4.1.2, it can last almost 2 days.
Thanks for your help!!