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Verify your ownership after factory reset
Because your device is protected, you'll need to either unlock your screen or enter your Google Account password if you need to do a factory reset. This ensures that you or someone you trust is doing the reset.
Expect to unlock your screen or enter Google Account information if you:
Erase your device's data using the Settings app
You'll be asked to enter your screen lock before using Backup & reset.
Reset your device in Recovery mode.
If you reset your device using the recovery menu, you'll need to enter a Google username and password that had been associated with the device.
Remotely reset your device with Android Device Manager.
If you remotely reset your device using Android Device Manager, you'll need to enter a Google username and password that has been associated with the device.
Important: You can enter information for any Google Account that has been added and synced to the device as an account or user profile, but not the guest profile. If you can't give this information during the setup process, you won't be able to use the device at all after factory reset.
Källa:
https://support.google.com/nexus/answer/6172890?hl=enClick to expand...