If your model number is the SPH-l710T, download the TWRP tar file from here
https://dl.twrp.me/d2spr/
Get the 3.0.2-0 from the top.
Download to PC and place it where you can find it.
SuperSU update zip from here
http://forum.xda-developers.com/showthread.php?p=23427715#post23427715
Download the TWRP/Flash fire installable Zip, stable, to PC and copy to your phone's SD card.
You can get Odin 3.10.7 from here.
http://forum.xda-developers.com/showthread.php?t=2711451
You install Odin on your PC and run it
Place your phone in download mode and connect to PC.
In Odin,under options, unchecked Auto Reboot.
If your phone connects to Odin you will see a blue com port.
Select AP and browse to the TWRP file you downloaded earlier and select it.
Wait till Odin is ready then press start.
Wait till Odin finishes and you get a green Pass above the com port.
Unplug your phone and remove the battery. Wait a few seconds and replace the battery.
Use the button combo to boot into TWRP recovery.
Select Install. Locate the SuperSU update zip that you copied to SD card and select it.
Swipe the arrow at the bottom to begin the flash.
Select Reboot-System.
When phone finishes boot, locate Supersu in app drawer and open it.
You should get a prompt to update binary and also to disable Knox.
That's it,you are Rooted. You can download a root checker app from the Play Store to verify.
