To root the device you are required to downgrade to 5.1.1. Recently ZTE has removed all the official ROMs for this device that contain 5.1.1 files. This was the most common way to downgrade, by downloading these files and side loading them with ADB. However, I have found a Romanian version of the 5.1.1 ROM that is suitable for the root process.
You will need:
Vodafone Smart Ultra 6
ADB Platform tools
Firstly, download the platform-tools.zip from: https://developer.android.com/studio...platform-tools
-extract the platform-tools.zip and place the folder anywhere on your computer.
Secondly, download the Romanian stock ROM from: https://bit.ly/2IwkUCT
-extract it and move the update.zip folder into the platform-tools folder.
Lastly, download the TWRP recovery from: https://androidfilehost.com/?fid=24591000424952165
Now, make sure you have the Android USB Drivers installed. You can download from here: https://developer.android.com/studio/run/win-usb
Now that is out of the way, lets flash the ROM onto your phone.
Reboot the phone into recovery. (Power button + VOL up (release the power button 2 seconds after "powered by android" logo, otherwise it will reboot)) Also plug in the phone to PC.
Now, select 'Apply update from adb'.
On the computer, head to the platform-tools folder and open CMD with that directory. (you know, the cd C:blah\blah\blah)
Then, type in
adb sideload update.zip
Reboot the phone and you should see Android 5.1.1 setup screen in the Romanian language. Set it to the language you desire and connect to Wi-Fi. Log into your Google Account and do not set up a lock on the phone.
Now, head to Google Chrome and download KingRoot apk: https://kingroot.net/
Install the APK and try to root. It should work.
Now, go into Google Play Store, and install Rashr Flash Tool: https://play.google.com/store/apps/d...tools&hl=en_GB
Move the TWRP recovery img file from the PC to the phone, and then open the Rashr Flash App and grant root permissions.
Scroll down till you see the 'Recovery from Storage' option. Select that and flash the recovery img.
Now, that should work. When it is complete, find and download the custom ROM you would like to flash. In my case, I will be using the MIUI 7 ROM. (links of other ROMs below.)
Transfer it to the phone and reboot to recovery. Once you are in recovery, wipe everything except internal storage and flash the ROM. After flashing, then you can wipe internal storage and reboot. You can also root if you desire.
You have now installed a custom recovery and a custom ROM to your phone. Give ya self a pat on the back.
List of ROMs you can install on this device:
MIUI 7: https://www.modaco.com/forums/topic/...beta-for-vsu6/
Flyme 220.127.116.11 LP: https://www.modaco.com/forums/topic/...e-os-51513-lp/
Lineage 14.1: https://www.modaco.com/forums/topic/...smart-ultra-6/
Lineage 13.0: https://www.modaco.com/forums/topic/...smart-ultra-6/
GIPSY V5: https://www.modaco.com/forums/topic/...ormanceonline/