[Galaxy Note 4 Q&A, Help & Troubleshooting] g00ey:
I've had my Note 4 for a while and after a few Lollipop update incidents I finally after a lot of hesitation decided to root my phone (with the TWRP bootloader) and disable the update notifier. Since then, I've always stuck to the latest stock version of KitKat 4.4.4.

Since I've rooted my phone, I made the following modifications that require root priviliges: I installed XPrivacy mod, YouTube AdAway mod, NoSafeVolumeWarning mod, PlayPermissionsExposed mod, and CrappaLinks mod for the Xposed framework. I also installed Titanium backup to freeze/uninstall the updater and AdAway. After XPosed was installed I had to change a line in /system/build.prop to 'ro.securestorage.support=false' to make 'S Health' work again. I did that with the 'FX' app.

That's it, I had made no more modifications and the phone seemed to work quite well for a month or so.

Two days ago I decided to try out Instagram, I've been quite wary with social apps but figured Instagram shouldn't hurt and everything was fine. Then I installed a bunch of dating apps, I started with Match.com and Tinder. Tinder didn't work because it required FB and Match didn't work because it refused to, probably because of denied permissions with XPrivacy so I gave up on them and uninstalled them.

But I also installed OkCupid and Motesplatsen and enjoyed playing around with these apps. They didn't seem to interfere with XPrivacy and worked rather fine. Motesplatsen was rather intense with sending me notifications of girls who watched my profile and sent me (rather strange) messages whereas OkCupid was rather calm.

Then something strange happened.

Yesterday I started noticing that the battery was draining considerably faster than normal during normal day. It was almost empty whereas it usually is half full after a full day, I also noticed that the phone was unusually warm. I forgot to put it on the charger and woke up today with a dead phone. I put it on charge and after about an hour the battery was full again.

When I tried to turn on the phone it was stuck on boot loop. I first tried disabling XPosed by "touch /data/data/de.robv.android.xposed.installer/conf/disabled" using the 'terminal' tool in the TWRP bootloader. It didn't help. I tried flushing the cache/dalvik cache but it didn't work either. Then I did a total factory reset, but that didn't work. I noticed that during boot, the phone froze so hard that it doesn't even respond to button pushes. I had to take out the battery to reboot (that's one reason why I never will buy S6).

So then I decided to flash the phone with stock KitKat once again using Odin and that finally restored the phone.

Now, here's one of my questions, how can things go so bad with a phone that not even a factory reset will fix it? We're talking stock firmware here, albeit it is rooted.

What boot logs could be worth looking into when such a thing occurs and what is the easiest way to extract them? The terminal tool in the bootloader seems promising, plus I saw a 'copy log to SD' option which I neglected this time.

I'm puzzled, does anyone know what happened? I made no root modifications in the process of installing these apps and they don't advertise themselves as needing root privileges. How can a seemingly inconspicuous app directly from Google play **** a phone up like that?