Please note that when you unlock or lock your bootloader, it will erase all the user data. It’s like doing a factory reset; so you want to back up everything. Also know that having your phone’s bootloader unlocked means that it is vulnerable and the system won’t be able to check for corruption. You will even get a warning during boot that says:
Your device software can’t be checked for corruption. Please lock the bootloader. Visit this link on another device: g.co/ABH. Press Power To Pause.So, only unlock the bootloader if you know what you are doing. Just use it to flash a ROM and then lock it again immediately.
Here are the steps to unlock and lock Android bootloader in Nexus 6P phone:
In Your Phone
- Enable the developer options by going to Settings > About Phone and repeatedly tapping on the build number 7 times.
- From the new Settings that appear (System > Developer options) make sure that it is turned on along with OEM unlocking and USB debugging.
- Connect the phone with a wire to your computer and give it the permission if it asks for it.
In Your Computer (and phone for confirmation)
- Go to run and type in cmd to access the command prompt.
- To make sure that everything is good type adb devices and you will see your phone under the List of devices attached.
- Type adb reboot-bootloader
- To Unlock the Bootloader, enter the command: fastboot flashing unlock
- Use the volume keys to navigate and power button to confirm the action on your phone.
- Type fastboot reboot to restart.