Using a modified version of DirtySanta, you can gain flash boot.img to any Android device.
I used it for gaining root acces on the Sprint LG G5 runnin ZV4 software, could be useful for other people too. Full guide on how-to is here, this is just for the source code of dirtysanta http://forum.xda-developers.com/sprint-lg-g5/how-to/guide-adb-root-rw-dm-verity-off-sprint-t3523496