fastboot reboot
6. Boot the phone into recovery mode by switching off and using Volume up button + Power button
7. Once you enter recovery mode, use the volume button to move up and down
8. Scroll down to Install zip and select it
9. Select Choose zip from /storage/sdcard1
10. Navigate to the location of SuperSu.zip and select it
11. Select Yes – Install SuperSU to confirm flashing
12. Return to the home screen (using the back option) then select Reboot