First lets hear which firmware have you installed (link t thread) and which pjantom kernel.
I can't even imagine how the battery be drained 100% in 30 minutes, from tests I have done and 2 and a half hours HD youtube video over wifi drains the battery about 51-56%, so thats way too much.
I am using stock ROM and kernel with few tweaks and today I had about 40% drain after 21 hours and 1 hour 20 minutes of screen on time (no calls no data)
All you need is rooted stock ROM 6.2.A.1.100, and it's quite easy to do.
The data you should simply backup, backup with stock backup, export your contacts, and then if you wish you can backup with titanium backup or other.
I also keep my phone backed up with my google account.
You won't lose data on internal storage only on device memory.