how can i unlock the bootloader?DISCLAIMER
As usual, you do anything described in this post at your own risk. No one but you is responsible for any data loss, bricking or damage of your device.
ADB means Android Debug Bridge, and it is software that you should always do have installed on your PC.
Make sure that you have the drivers for your phone installed on your PC.
If not, you can download and install them from here
You must also install: Minimal ADB & Fastboot, you can download the software
Your device needs this with unlocked bootloader
Make sure you have enabled 'USB Debugging' and OEM Unlocking on your device
Settings -> Advanced settings -> Developer Options
PAY ATTENTION: If you do not see the Developer Options menu you need to do this:
Settings -> Device Info -> tap 6 or 7 times on the 'ZUI version' entry
A pop-up should appear, telling you 'now you are a developer'
And now, how to install:
1.Reboot phone to Fastboot mode (via adb -type adb reboot bootloader)
2.Download patched vbmeta and TWRP recovery
3.Extract it to folder with minimal adb and fastboot
4.Open cmd in this folder and type fastboot --disable-verity --disable-verification flash vbmeta vbmeta.img
5.Then type fastboot reboot bootloader
6.Type fastboot flash recovery twrp_3.3.1_decrypt_works_by_alexeei.img
7.Press volume - and select Reboot recovery, then press power button
All functions (may be if not, please say). Also TWRP now see exFAT microsd.
Thanks wzsx150 for it's TWRP for Lenovo Z5 Pro GT, some decrypt stuff taken from it.