(Q - Short) Note 4 5.1.1 Root Failure - Bootloop (Can't flash / factory reset)

Hi.

Phone Info:
Samsung Galaxy Note 4 - (updated to) version 5.1.1, Sprint carrier, SM-N910P.

What I did:
Tried to root my 5.1.1 device via (presumably, now) incompatible protocols:
galaxynote4root dot com/galaxy-note-4-root/how-to-root-galaxy-note-4/
Tl;dr I used Odin and CF Auto Root via USB cable (Computer & Download mode on Phone).

What happened:
Root seemed to work, but immediately upon reboot, my device went into a perpetual boot loop.

Currently:
I've tried flashing, downloading proper firmware; fails.
I can access download mode & recovery mode.
Recovery mode tells me my dm verity verification has failed, so any attempt to clear the cache and factory reset has failed.

I've heard the possibility of a custom ROM fixing this issue, but I don't know the half about where to even begin there, and I'm so beyond frustrated. Any ideas are more than appreciated.

Jenn