I will trying and give you the steps but you will need to connect to the pc anyway. I am assuming you are on stock recory and have no twrp installed. root is much later and is done after cm133 and gapps are installed
1. go into settings ---> about phone
2. hit build number 7 times until you have developer options
3. Go into developer options and set these to on if they aren't already. If they are continue to the next step
Advanced Reboot
OEM unlock
allow debugging and if it gives a prompt when you connect the usb to the pc allow it and set always remember choice.
4. Power off your phone you should get a few options select bootloader this should take you to fastboot mode
5. Assume you have this file
https://dl.twrp.me/onyx/twrp-3.0.2-0-onyx.img.html
6. In cmd type
7. fastboot flash recovery twrp-3.0.2-0-onyx.img
8. fastboot boot twrp-3.0.2-0-onyx.img You should be in twrp
9. install cm13 and gapps like before
reboot but remember to say no to supersu
10. when all goes well and you are up and running
11. go into settings ---> about phone
12. hit build number 7 times until you have developer options
13. go into developer options there will by an options called root access enable that
Click to expand...
