Today I had it in flight mode, it stayed hot and kept draining the battery.
The battery isn’t bloated, I’ve already tried the battery reset (twice), and I’ve tried it without SIM and SD card. Better battery stats is installed, but I do not know how to read what it is telling me!?
Pfuideifi, I do not have any Facebook at my device! 
But indeed I suspect that maybe XPrivacy/AFWall+ is blocking anything that is running wild because of that. But how could I determine that? The battery graph keeps saying, it was no specific app, and the CPU monitor doesn’t see anything using that much CPU.
I do not think so. The phone is very newly installed, i am blocking scripts in my Fennec (NoScript) and that kind of computer scientist that thinks octuply before installing anything.
Unfortunately I was browsing the forum with my phone, thus in a private tab without logging in. Sigh.