[Galaxy Note 4 Q&A, Help & Troubleshooting] BriBriGoo:
Battery Optimization, remove all apps - now fully functional

My N915G has been rebooting, freezing, hanging for about 10 days now. Unusable, driving me nuts. But I don't need to tell YOU that.

I have read all the posts (this is my first post btw) and begun a spreadsheet on all the possible repair directions.

SuperSU - I'm not sure if there is an issue here, but this was the first thing to pop up on the login screen when the problem started. It requested an update and then things slowed down, rebooted and the problems began - I am not dissing SuperSU though, it's great. This is just how it happened for me.

Wakelock - Whilst this appears to work on a lot of your phones (and got me thinking), it still seems like a band-aid solution to me.

Firmware - All Marshmallow software appears to not improve the situation (Rooted or not)

Partitions - This is something I had a look at and might have helped somebody but I realised it probably shouldn't be the first thing I try.

Overheating - This was an issue for me and I think a few people let their battery get too hot and required replacing.

Plugged in - My device was affected by whether it was plugged in suggesting power issues also.

Google - My device was fine before I signed into Google after flashing.

eMMC – I don’t think I saw this fault BUT

Boot Error – My phone regularly displayed the following at boot:

BOOT RECOVERY MODE (GREEN)

CHECK BOOT PARTITIONS.. (WHITE)

sbl1 partition doesn’t exist (RED)

ODIN MODE (HIGH SPEED) (RED)

PRODUCT NAME: SM-N915G (WHITE)

CURRENT BINARY: Samsung Official (WHITE)

SYSTEM STATUS: Custom (WHITE)

REACTIVATION LOCK: OFF (WHITE)

KNOX WARRANTY VOID: 0x1 (0) (WHITE)

QUALCOMM SECUREBOOT: ENABLE (CSB) (WHITE)

RP SWREV: S1, T1, R1, A1, P1 (WHITE)

SECURE DOWNLOAD : ENABLE (BLUE)

UDC START (RED)

Reasons for Software to be the culprit

DjStep - Had 2x identical Note 4's fail at the same time

Wakelock - Wakelock is software and it 'patches' the problem

Firmware - I installed 5.1.1 and the 'Hanging' remained but the 'Rebooting' stopped.

Steps I tried that failed (Starting point - Rooted Stock Marshmallow 6.0.1 Nova Launcher)

Used ODIN, flashed newer and older MM ROMs and Rooted each time.

Tried taking the External SD out.

Flashed 5.1.1, still hanging.

A Solution

(SM-N915G 6.0.1 Australia Telstra) (NB, I was using 5.1.1. I used Samsung Smart Switch to update ‘Initialise’ to current MM version. Problems did not occur until after Google sign-in)

After booting, I signed into Samsung only. Not Google.

I let all Samsung stock apps update first (on and off charge and overnight and into the next morning).

I let this occur so as to isolate the freezes from the heavy system use of updating Many apps.

Settings Gear-->Battery-->Battery Usage-->3x Dots-->Battery Optimization-->touch 'Not Optimized' to select 'All Apps'.

(This next bit takes a while, relax)

Grey Everything, so nothing is power optimized. System apps and regular apps.

Then Settings Gear-->Battery-->(App Power Saving)DETAILS-->

Turn Off App Power Saving.

Reboot

My phone went straight back to fully functional and as fast as it should be when new.

Problem:

When I installed another app, I think it was Firefox, the problem started again.

I went back to Settings Gear-->Battery-->Battery Usage-->3x Dots-->Battery Optimization-->touch 'Not Optimized' to select 'All Apps'

Greyed out Firefox, and stability returned.

*This step tells us a great deal about the problem*

It seems to be a Marshmallow Software 'Power Saving Feature' that is not working on the Note 4 / Note Edge hardware.

I am unfortunately not a Developer...

Tasker could perhaps be used to install apps without 'Power Saving' selected. Or

An app that unchecks all the apps power settings in one go maybe. (Install App / run PWR-APP)

3C Toolbox (Payed on App Store) might hold the answer also.

In my opinion, Samsung has created this problem and should solve it. The problem is the Firmware incompatibility with our devices. Telstra (and other carriers) might have just passed the newer 6.0.1 version on face value without fully testing as they should.

Thank you everyone in the posts before mine, you know who you are. This all came from YOU!

So what now?