1. Power on the phone.
2. Tap 7 times on "Build number" in "Settings"-"About phone" to enable "Developer options",
   enable "USB debugging" in "Settings"-"Developer options".   
3. Connect the phone to PC with USB cable, install drivers if needed.
4. Select device in ADB settings.
5. Press "Activate diag" from "Service" tab.
6. Press "Unlock" button for direct unlock.