So then, It's not a problem of the unbrick tool, that is actually working properly. The thing is that you didn't know how to do a correct process to migrate from cm rom to global...
The first thing you should do is reboot the phone into fastboot mode (power+vol. Down). Then, connect the phone to the PC and type the next commands in the cmd:
in order to see if your device is being recognized
Code:
fastboot oem nubia_unlock NUBIA_NX629J
to unlock the bootloader
in order to make your phone able to boot with a modified software. In the moment you will enter this command, you will see a screen advising you about your data (it'll be erased once you accept to unlock flashing).
After that, you can reboot your phone, that will show you an screen advising you that the bootloader is open. Accept and continue without problems.
Tell me if you have been able to make your phone boot.