[Galaxy Note II Q&A, Help & Troubleshooting] Rickav:
An update on this: Since then, I have wiped everything (internal storage, data, cache) through TWRP and then caved into to flashing this NE1 stock rom through Odin V3.09 following this guide. What followed was this:

1. Open up Odin V3.09, ensuring I've already got the Samsung Drivers installed beforehand

2. Place phone (completely clean phone with nothing but the TWRP V2.8.6 recovery used wipe everything) into Download Mode with Power + Home + Volume Down

3. Connect the two up with the official Samsung cable the phone came with and the device shows up "Added" on Odin

4. Select the MK9 rom tar file through the AP (formerly PDA) tab.

5. Start it up

6. Wait for it

7. This takes longer than I previously imagined

8. The deed is done, Odin says "Reset" and the phone starts to reboot

9. Soon after, the phone actually reboots to the stock recovery screen where a whole bunch of errors appears along the lines of failed to mount /system repeatedly as well as /cache amongst others

10. From there I choose "wipe data/factory reset" then "wipe cache partition" for good measure before choosing reboot

11. Since that reboot, the phone is stuck on the "Samsung Galaxy Note II GT-N7100" splash screen indefinitely

12. Was really hoping this wouldn't happen...

Can access both stock Recovery and Download mode using the relevant key combinations but nothing else apart from that. Hence, I tested by changing some variables by starting the wipe with TWRP V2.8.3 (reputedly more stable) and choosing an older MK9 firmware with identical results. In amidst this, I remember flashing a CM12.1 rom following a full wipe and it was simply stuck on the boot screen animation indefinitely. That's a bit worrying to be honest, but I wasn't dwelling on it at the time as I was only looking for positive results with stock roms. Currently, I'm downloading France's 4.4.2 ND3 firmware which I distinctly remember as being one of the few stock firmwares I had flashed a year or so back successfully to revert to stock rom temporarily for some reason. Hence, here's wishing history repeats itself and I'm back on stock rom once the download finishes in just under an hour from now.

In the mean time, if anyone has any other ideas/tips or anything I may have missed, I would really appreciate hearing about it. Currently, in Download mode, Odin reads:

Product name: GT-N7100

Custom Binary Downloads: Yes (11 counts)

Current Binary: Samsung Official

System Status: Custom

Knox Warranty Void: 1

RP SWREV: A2

I don't mind losing Knox or warranty as warranty has run out anyway. Very keen to get back to normal working conditions with at least stock with properly functioning mobile network connection so then I can root and update to CM12.1 at a later stage. In addition to flashing a different stock firmware, I'm also planning to try PhilZ Recovery for wiping before flashing the stock rom, however, I only found zip file for V6.46.3 as many of the downlinks on their main download page for N7100 is down meaning I have to first flash TWRP to install the PhilZ Touch zip. Perhaps flash modified stock, like Phoenix or DN4 to get mobile services back? Maybe something else? Again, thanks for taking to time to read this.