For those, who don't know, there's how to unlock/lock bootloader without erasing data:|
1. Turn off the phone
2.Hold power & volume down, keep the volume down button pressed!
3.Connect phone to PC, on PC fastboot type:
fastboot oem unlock
still keep the volume down pressed
when phone starts to reboot, release volume down(when black screen appear), for me, when it starts to reboot, I disconnect the phone too
5. Now phone should be unlocked without deleting data partition.
Tested, for me worked 100%, but you need to be careful, or you will lose data!
Full Credit goes to Ondraczsk from XDA.
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