IntroductionThis is a guide to backup and restore the QCN, and to edit other's QCN in case you lost your IMEI and you don't have a backup of your QCN. There are other ways to do some steps (the most popular is via Fastboot) but I'm gonna describe the way that I think it's not only the safiest in our Z6 Pro but also valid for both locked and unlocked bootloader.
Disclaim: even having tested these steps more than enough times, I'm not responsible for any damage in your devices, do things at your own risk or don't do it.
Post 1.- Backup QCN
Post 2.- Edit IMEI in QCN
Post 3.- Restore QCN (Fastboot and QFIL methods)
- QPST installed (which includes QFIL). You can download it here.
- Lenovo and Qualcomm drivers installed. Download them here. (thanks @benjieb )
1. Enable Diagnostics mode in your phone.
a) If you're using an stock ZUI ROM, open dialer and dial *#*#33284#*#*
In the next screen select "For qmi test"
b) If you're using a custom rom you can try the dialer method but most likely you will get nothing after dialing the code. If this is the case you still can enable the Diagnostics mode but you need root privileges. Open a Terminal Emulator app and type this:
su setprop sys.usb.config diag,adb
If you get "Select port" instead, press "Select port" button top in the right, select your device and press OK. Your device should be shown now.
2. Backup the QCN
Press the "Tools" tab and a menu will open, select "QCN Backup Restore"
In the new window you can choose the name for the backup file, just name as you want and leave untouched the .qcn extension. You also can choose where will be stored. Select the "multisim" option and press Backup.
Once the backup it's done, check the generated file size. A normal backup is around 310Kb, if your file is significantly lighter you can suspect of a damaged file. In this case I suggest installing stock ZUI rom and use the dialer method.