[Verizon Galaxy Note 4 Q&A, Help & Troubleshooting] Jyosua:
I'm actually pretty frustrated right now. This is not my first time messing with an Android phone. I've had several in the past, have dabbled in installing various custom roms, etc., but the guides for this phone seem to universally suck. I have a developer edition Note 4 that I rooted and unlocked the bootloader when I first got it. I bought the developer edition because I knew the bootloader could be unlocked easily, which I thought was supposed to make installing ROMs easier and less hacky. Now, It's been stuck on KitKat 4.4.4 for over a year and a half, and I wanted to update it to 6.0, but it seems like a massive pain in the ass. What gives? I'll link to all the guides I've followed thus far.

First, I found this: http://xdaforums.com/note-4-verizon/development/firmware-safe-upgrade-to-marshmallow-t3402727

This is all I wanted to do. This guide told me to upgrade and (re?) unlock the bootloader via this guide:

http://xdaforums.com/note-4-verizon/development/howto-bootloader-unlock-upgrade-to-t3398144

This guide, for whatever the reason, tells me that even if I have a DE, I should install this other ROM for some inexplicable reason, then re-unlock the bootloader. Okay then. That points me to ANOTHER GUIDE:

http://xdaforums.com/note-4-verizon/general/note-4-verizon-bootloader-unlock-t3358913

And this guide tells me I have to root to unlock the bootloader (a reasonable assumption) but doesn't tell me how. I don't know how I did it the first time dude, it's been over a year and a half! So, with some searching I found this freaking 40 step guide:

http://xdaforums.com/note-4-verizon/general/easy-guide-how-to-root-verizon-galaxy-t3454593/page2

Now, not only is this guide stupidly long, its 'helpful' link to all of the software needed is broken. So I searched for the crap myself. I tried KingRoot, which rooted at first, but had other issues. I switched to Kingo Root, which seems to have worked better. I was able to get the n4-fix file to /data/local/tmp, change the permissions to be able to execute it, and run it. It seemed like I was finally making some progress. Except, when the phone restarted, it got stuck in a boot loop at the Verizon logo screen.

I don't know where to go from here, but I am really at my wit's end on this one. I've been working on this for 2 days. And before anyone asks, yes, I backed up my aboot, and I also have backups using TWRP from when I first got the phone and from its most recent state before I changed anything. Though, I don't know how to restore aboot, so if that's a problem, I'm pretty screwed.

Help would be greatly appreciated, before I throw my phone against a wall and buy a new one. I like this phone. But it really started to get bogged down and stop working right, so I thought it was time for an Android upgrade.

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I got it working, after hours. There were a couple things at play here, chief among them is the fact you have to remove the SD card from the device after attempting to unlock the bootloader, because it causes a boot loop. I also had to do a factory reset after flashing even in some cases where it wasn't specifically stated. Pretty frustrating. Anyhow, hopefully I don't have to ever go through this again any time soon. I made it to 6.0.1.