[ZTE Nubia Z9 Mini ROMs, Kernels, Recoveries, & Oth] navin_n:
I have made this thread for those users who have bought Nubia Z9 Mini from China and have no Google Services. I have modded the official stock ROM with Google Services. This is PURE stock without any additional tweaks except Root and unnecessary preinstalled Chinese apps removed. You can visit my Google drive to download this custom ROM and I have also included the recovery tool that will install English TWRP recovery.

THIS ROM IS FOR CHINESE VERSION NUBIA... IF YOU FLASH IN INTERNATIONAL/INDIAN VERSION, YOU WILL HAVE PROBLEM WITH NETWORK/DATA CONNECTION (Refer to post below to overcome this issue)

GOOGLE DRIVE FOLDER TO DOWNLOAD THE ROM AND RECOVERY TOOL​

STABLE RELEASES:

Version V4.52 Android Version 5.1.1 (with updated UI 5.0)

OFFICIAL STOCK INTERNATIONAL VERSION (CHINESE NUBIA):

Version V3.67 Android Version 5.1.1

NUBIA Z9 MINI ELITE (3G RAM):

Version V4.02 Android Version 5.1.1 (with updated UI 5.0)

RECOVERY TOOLS:

TWRP 3.0.0-0.1 (ENG/CN) (Credits to romxz.cn)

RESTORE TOOL:

Nubia Restoration Tool(Chinese) ---> Use this tool to restore the bricked Nubia devices. Works on all Nubia Devices.

GUIDE TO INSTALL CUSTOM RECOVERY + CUSTOM ROM:

REQUIREMENTS:

1. Be sure to backup all important data (contacts, messages, call records, etc.) before proceeding.

2. Working Windows PC with ADB Drivers installed - without proper installation of drivers the process will not be successful.

STEPS:

(If you need only Custom Recovery, then follow the steps from 2 to 7, other steps you can skip)

1. Download the required zipped Custom ROM and copy it to the root directory of External SD card or Internal SD card.

2. Download the Recovery Tool exe file from the link above.

3. Enable USB debugging mode. ("Menu Button" >> System settings(Settings) >> About phone(On the phone) >> Tap 6 times on Build number>>"Back button">> More >> Developer options >> Enable USB Debugging)

4. Connect the phone to the PC.

5. Execute downloaded Recovery Tool exe file.

6. In PC, new window will open. Input your choice of Recovery accordingly. (Allow the Authorization Request in the phone)

7. Follow the steps on-screen until all completes.

8. If the Custom Recovery was flashed successfully, you will get TWRP recovery menu.

9. Perform wipe data/factory reset and wipe cache partition.

10. To flash the firmware: Select "Install ZIP" >> "choose zip from sdcard0 or sdcard1" depending on which SD card you have copied the ROM, external or internal >> Select Custom ROM >> Flash selected ROM.

11. Wait until you get the confirmation of successful flashing.

12. Reboot the phone by selecting "reboot system now".

13. DONE. (Initial boot may take some time so have patience.)

STEPS TO GET DATA WORKING ON 5.1.1 BASED STOCK ROM's (If you have flashed Chinese Version in International Version)

Original Source: 4pda.ru Forum and Thanks to JohnMcClane, im190610, олежек1975, Апостол666, Lepi, isnest, alexonik, kakawkin

Compiled and updated by:mad:pradipsoman

1. First ensure that you are on a Nubia factory ROM. Download NubiaTools and jd_gsm_3.61.zip from this Link

2. Enable USB debugging on your phone and enable RSA security key box shown, when connected to your PC.

3. Type the following code on the Dialer: *#7678#

4. You will see two blank boxes open up. Tick both boxes you see.

5. Now install this driver on your windows 7 with your mobile kept on.

6. Once this serial port driver is installed check it on your Device manager-Ports settings. It should show USB Diagnostic MDM port. Also see that the driver is installed WITH THE PHONE ON and not off. If you power off and press power-volume-up/down etc. the wrong driver gets installed automatically which will not work. This is the most important step in this whole process. No correct driver and you can't get NubiaTools to work.

7. Go to the Properties of the port and the tab Port Settings in the upper value of exhibiting 115200 bps.

8. Now start Nubia tools on your PC. Before that disable any antivirus programs like NAV as it will give a false alarm on Worm/Trojan detection as soon as you run the NubiaTools file.

9. Select Tools / Settings. Set baud rate as 115200

10. Select back up and press Settings tab in backup, and set baud rate as 115,200

11. Once your Nubia shows up in the Port field, Press START to choose the place where to save the file QCN and click Start All on the panel. After a small amount of time you have your QCN backup.

12. Check if the QCN file has been backed up at the location you chose to.

13. Now follow the directions in the zip file contents to flash the patch files inside the jd_gsm_3.61 zip file (use patch.bat file. Your mobile and PC should be connected and communication enabled in ADB mode.). If it gives error then copy the patch files directly to the root directory of SD card and run the batch file.

14. Now using Nubia tools use Restore to restore the QCN file to your mobile. (Forgetting this step will leave your phone without IMEI)

15. Now you can do a reboot and you will have Data enabled for 5.1.1 based Nubia factory ROM’s and also the unstable Data issue with 3.14 to 3.20 Rom’s also would be rectified.

USEFUL TIP:

If the device is not responding or having black screen, press "Power Button+Vol up+Vol Down" together for sometime until the device vibrates.

The device will boot up automatically.

For Other Custom ROMs you may check these sites. (May require translator as these sites are not in English)

Mod edit: Links removed.