Flashing a highly customized AOSP or LineageOS ROM might break the native "dual-screen extended mode" that ZTE originally coded. You will usually be able to use both screens for mirroring or running separate apps, but apps that stretch seamlessly across the gap might experience UI bugs. Gaining Root Access
Copy the unextracted file to the root directory of a FAT32-formatted microSD card. Insert the card into the Axon M. zte axon m z999 firmware best