The LG V20 has anti-theft, which is an always on feature and can affect how you master reset the device.
To turn off anti-theft protection, follow these steps:
- Sign out of any Gmail accounts assigned to the device
- From the Home screen, tap Settings > General tab.
- Tap Accounts & sync > Google.
- Tap on the email account assigned to the device.
- Tap the Menu icon.
- Tap Remove account.
- Tap REMOVE ACCOUNT to confirm.