Hello mate, the note 4 is so old it never had OEM lock option, you need to use a tool called ODIN to flash images such as TWRP Recovery.Hello. Thank you for this great update for our old devices. I'm having an issue starting the whole process since I can't find a way to unlock OEM in my 910U. Can I still flash the TWRP and update via Odin without unlocking? And if not, is there any method to follow? I've tried many things like fastboot (which doesn't detect the phone), recovery mode (using reboot to bootloader via recovery only reboot the device), and of course, developer settings, which doesn't show the necesary option to unlock OEM. Any help is apreciated (and excuse the novice questions)
This WiKi covers the process for TWRP. https://sourceforge.net/p/galaxy-note-4-exynos/wiki/TWRP Custom Recovery Guide/
since it is the first time you are flashing a recovery, you will use the ODIN option, ignore the part about encryption unless you plan on using encryption with this ROM. the note 4 also does not ship out of the box with encryption enabled (so you dont have to format data at all after installing TWRP, as opposed to modern android devices)
Regarding how to install the ROM itself, just download the latest lineage (or RR OS) build from here https://sourceforge.net/projects/galaxy-note-4-exynos/files/LineageOS-17.1/
N910U is trhpltexx.
If you want google apps, they are linked at the first post of this thread, people have been facing issues with opengapps, which is not surprising, so you should use bitGapps instead.
if you want root, flash Magisk aswell