Install TWRP recovery.
Boot to TWRP (Go to bootloader screen by Power off, followed by Vol – and Power On button pressed simultaneously, then Power button released; Next Vol – to highlight recovery menu, and press Vol +)/
Install Superuser latest package from TWRP.
Reboot, and install SuperSU app from Play Store.
Also install busybox with Busybox installer by sterricson, from the Play Store.
Joel G Mathew, known in tech circles by the pseudonym Droidzone, is an opensource and programming enthusiast.
His favorite pastime is grappling with GNU compilers, discovering newer Linux secrets, writing scripts, hacking roms, and programs (nothing illegal), reading, blogging. and testing out the latest gadgets.
When away from the tech world, Dr Joel G. Mathew is a practising ENT Surgeon, busy with surgeries and clinical practise.