[Galaxy Note5 General] droidvoider:
If anyone is interested in a partial downgrade to allow the use of dirtycow here are my files. This was tested to downgrade the N920AUCS4CPK1 kernel to the N920AUCS3CPJ1 kernel by flashing boot.img and recovery.img of the previous baseband. (Oddly allowed? sw rev check fail doesn't apply to these files).. You can also use the userdata.img file which is not well tested, but I'm now using that also.

These are Odin flashable tar.md5 files after you unzip them. IF HAVE NOT tested these in Odin EXCEPT the 1st option, boot.img and recovery.img only.

1. N920AUCS3CPJ1 boot.img and recovery.img to be flashed on top of an already installed/working Note5 w/ N920AUCS4CPK1 installation.

https://mega.nz/#!nwFUVQaC!R3inD-QNEfLKmLGnVnMuAHG10WaMzvivdNn5samhSkA

2. N920AUCS3CPJ1 boot.img and recovery.img with N920AUCS4CPK1 system.img and userdata.img .. (This is for a full setup, use this AP file instead of PK1 AP file)

https://mega.nz/#!XsdxAR7D!RrmYvOgDYdt72MDsV7OmpW-eM5gHqSQu7clwrOIdSQk

3. This is the experimental AP file replacement. N920AUCS3CPJ1 boot.img, recovery.img and userdata.img with N920AUCS4CPK1 system.img. (CAUTION: untested)

https://mega.nz/#!e0ESUZBT!QbLR9Ew0-DFsOpte2wN-wCeRRfWQEATjyKlmuSn8hP8

Note: How I created them is detailed in the zip file.

(Downgrade isn't too likely at the moment I have no earthly idea how I would get rid of sboot.bin "the locked bootloader". The rest of my efforts are just root while preserving knox container)

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*********************************SEARCH FOR ROOT*****************************************

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****************Note 5 64 bit hacking tools. Readme has links to sources*******************

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No root yet, just the beginning tools right now. (find a way to do something? please share this community needs it!)

Added: dirtycow, applypatch, app_process64, run-as and cowroot (run-as and cowroot don't work, even if cowroot worked it would crash in 20 seconds)

https://mega.nz/#F!wQVggApJ!Zv5wojVW5kiFi2crDDu02g

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Warning: The Note 5 is cool in a way to hack because most things you do will be undone when you reboot. I've altered things in / and /system/bin multiple times without any lasting effects! If you do modify things concerning knox permanently she won't boot. If you install a priv-app twice to make it stop you can also crash the phone out when playing around with knox. (refering to my little trick, see my thread on it. You reinstall a system/priv-app using adb install -rtsd <apk-name-you-adb-pulled-from /system/priv-app/> <=== oddly allowed. On another note patching certain things with dirtycow in /data will cause a sudden reboot.

If you patch app_process64 your phone will go dark, things that are important stop working. I personally do not want my phone in this state for long so I plan out things to try then get out quickly. I have disabler going, but I am not experiencing any cause for concern such as overheating, mass battery draw or odd screen handling. besides it going darker with app_process

Super dangerous expensive game be sure you want to play the entry fee is high. And backup your data you may never see this phone working again.

Project stopped someone else can take over without giving credit. Please don't give credit I don't want my name on this :) The tools on my github will be left up and I will help you compile any idea but officially I don't need to downgrade, and I wanna buy a unlocked phone