How to flash(you need recovery - TWRP is better(marshmallow support)):
1. MAKE BACKUP!!!
2. Push baseband and ROM to sdcard (copy MK71.2-d838-201704281402-UNOFFICIAL zip and LP Baseband to sd card)
3. Make WIPE dalvik, data,cache(from recovery)(advanced wipe in twrp)
4. Install lollipop baseband
5. Install ROM
按照这个步骤安装