[X Style (Pure) General] eigerzoom:
Thought I would make a thread, which could help someone.

My bootloader is unlocked

I was using Marshmallow LOS 13 unofficial build by Qbanin.

But these directions should be the same for anyone on MM unlocked.

You will need to know how to use ADB from PC and have platform-tools.

The reason I upgraded to 14.1 unofficial instead of official is because official requires the MM modem, and I had already flashed the stock nougat rom when i started looking for roms to flash.

Download the Nougat Stock Firmware:

https://androidfilehost.com/?fid=889964283620765304

Drop the contents of unzipped stock nougat into your platform-tools folder.

Hit the shift button and right click the mouse and 'open command window here'

Connect your MM device to your pc - booted into your current rom with usb debugging enabled

In the command windows type 'adb devices', you may need to confirm access on the screen of your phone, and try the command again.

Make sure your device is listed and authorized.

Type in the command window 'adb reboot bootloader'

Your device will reboot into the bootloader and is ready to program

Run these commands to flash stock nougat, make sure each command succeeds.

If they do not, run any command that fails multiple times until it succeeds and move on to the next, if a command fails more than 5-10 times in a row, start over from the beginning.

fastboot flash partition gpt.bin

fastboot flash bootloader bootloader.img

fastboot flash logo logo.bin

fastboot flash boot boot.img

fastboot flash recovery recovery.img

fastboot flash system system.img_sparsechunk.0

fastboot flash system system.img_sparsechunk.1

fastboot flash system system.img_sparsechunk.2

fastboot flash system system.img_sparsechunk.3

fastboot flash system system.img_sparsechunk.4

fastboot flash system system.img_sparsechunk.5

fastboot flash system system.img_sparsechunk.6

fastboot flash system system.img_sparsechunk.7

fastboot flash system system.img_sparsechunk.8

fastboot flash system system.img_sparsechunk.9

fastboot flash modem NON-HLOS.bin

fastboot erase modemst1

fastboot erase modemst2

fastboot flash fsg fsg.mbn

fastboot flash bluetooth BTFM.bin

fastboot erase cache

fastboot erase userdata -w

fastboot reboot

If your device reboots into bootloader repeatedly run this command:

fastboot oem fb_mode_clear

fastboot reboot

Your device will reboot, wait a while during Nougats first run.

Once Nougat is loaded and you pass setup, enable developer options and then ADB usb debugging.

run 'adb devices' command again and confirm the device is listed and authorized.

Download latest official TWRP 3.2.1.0

https://eu.dl.twrp.me/clark/

rename the file to twrp.img and place in the platform-tools folder

Download LOS 14.1 Unofficial (the latest build 2/23 is for MM modem: avoid)

Grab the 2/18 build or read around the forums for latest compatible build

https://androidfilehost.com/?w=files&flid=131793

Move the file to the root of your external sd card via MTP.

Download ARM64 7.1 OpenGapps and move to root of your external sd card

http://opengapps.org/

Run these commands in the command prompt

adb reboot bootloader

adb flash recovery twrp.img

Press 'down vol' for the recovery option and then press the power button

Phone should reboot into TWRP recovery

Allow TWRP to modify contents by swiping at the bottom.

Remember TWRP makes you swipe if your screen shuts off, so you may need to swipe twice to peform operations, ALWAYS PAY ATTENTION IN TWRP.

Select WIPE in twrp, and then ADVANCED WIPE.

Select the Data checkbox and hit the Repair or Change File System at bottom.

Select CHANGE FILE SYSTEM at bottom right.

Select F2FS and proceed with the format.

Select WIPE (again) from home screen choose to wipe dalvik,system,internal & cache

Select INSTALL from home screen and choose the LineageOS 14.1 build.

You will need to SELECT STORAGE at bottom left and choose your external card.

Add the openGapps 7.1 to the install queue as well.

Swipe to confirm flash and let the new rom and gapps install.

After complete wipe dalvik/cache and reboot.

Enjoy your new rom.

I also flashed systemless root in twrp.

https://drive.google.com/file/d/1GjKdxvoTi9YCU43HIy2XTTcB-bGnNn84/view?usp=sharing

This is for unofficial 14.1 only using the 2/10 or 2/18 build only.

The 2/23 build as I understand is a test build for MM modem only.

All future builds should be verified around the forum with hashbangs notes/recommendations as they do not exist at the time of this post.