You don"t need to have root to apply this procedure. Your bootloader doesn"t have to be unlocked.
This has been tested with C6902, 14.5.A.0.270 , Lollipop 5.0.2, Customized TW version, but it should work fine on any other customization of 14.5.A.0.270.
This procedure installs superSU root binaries and busybox on your system.
Requirements
1- Upgrade to Lollipop 5.0.2. Either flash an ftf using flashtool or if you are in a region where the update is available take the OTA. You can get the unmodified Customized TW version from here.
2- Make sure your PC can communicate with your tablet via adb.
The success of this method depends on following the procedure very carefully. So read the instructions and make sure you understand every step before you try it.
Procedure
1- Install and run Kingroot 4.0. You can google and download it or you can use the one in the attached zip file. When Kingroot runs it is all in Chinese, but basically you need to be connected to the internet for it to work. It will do its thing and show progress up to 100% after which you can exit the program. Now your phone is rooted. The following steps replaces the Kinguser with SuperSU.
2- Unzip the attached file in your adb directory and then open an adb terminal and make sure the PC can see your phone (you can check that by typing adb devices). Then type the following:
Code:
adb push su /data/local/tmp
adb push busybox /data/local/tmp
adb shell
3- In the shell that you get type the following and make sure you give the access permission when the tablet prompts you:
Code:
su
4- Continue by typing the following commands:
Code:
mount -o remount,rw /system
cat /data/local/tmp/su >/system/xbin/daemonsu && chmod 0755 /system/xbin/daemonsu
cat /data/local/tmp/busybox >/system/xbin/busybox && chmod 0755 /system/xbin/busybox
daemonsu -d &
The key is to keep this session running while you continue with the rest, so be careful with typos and monitor this window for any errors.
5- At this point, leave the adb terminal window running and go to your tablet, open the Kinguser app, open settings (the wheel at the top right corner of the screen), Root authorization setting, and Remove Root permission. The app may self-uninstall.
6- In any case, after this is done, uninstall the two or three remaining Kingroot apps hat are still on your tablet (Kinguser, KingRoot, and the other one with the blue icon and Chinese text under it).
7- Back to the adb terminal, and type the following: