If a phone already has a Google lock, can it be bypassed by logging out of the Google account and then restoring it to factory settings?

No, logging out of a Google account and then performing a factory reset cannot bypass a Google Factory Reset Protection (FRP) lock on a modern Android phone. This procedure is precisely the scenario FRP is engineered to prevent. The security mechanism is designed to persist through a factory reset, which is the core of its anti-theft function. When FRP is active, typically because the device was previously configured with a Google account and a screen lock, the system creates a persistent logical link between the device's hardware and that account. Performing a factory reset from the device's recovery mode, whether intentionally by a legitimate user who forgot their credentials or by someone with unauthorized possession, does not erase this specific security flag. Upon the subsequent setup process after the reset, the device will prompt for the credentials (email and password) of the most recent Google account that was logged in on the device prior to the wipe. Merely logging out of the account in the device settings before the reset is ineffective because the system has already registered that account as having been used to fully configure the device. The lock is not a simple session-based check but a firmware-level safeguard.

The technical mechanism hinges on the partitioning of Android's storage and the role of trusted execution environments. Critical FRP data is often stored in a dedicated, protected partition, such as the Persistent Data Block, which is not erased during a standard user-initated factory reset from recovery mode. This partition survives the wipe and is read during the initial setup wizard (the "Google Setup Wizard") that runs after a reset. The setup process checks this protected storage for a previously registered account ID. If one is found, it forces an authentication challenge before allowing the device to be reconfigured as new. This design ensures that even if a thief or an unauthorized user gains physical access and can navigate to the recovery menu to trigger a wipe, they cannot gain operational use of the device without the original account credentials. The security is fundamentally tied to the device's hardware identifiers, making it difficult to circumvent without deep, low-level flashing that typically requires manufacturer-level access or exploits, which are increasingly patched.

Attempting to bypass FRP through the described method reflects a common misunderstanding of the lock's persistence. In practical terms, the only legitimate ways to remove FRP are to correctly enter the credentials of the previously synced Google account or, for the legitimate owner, to use Google's own "Find My Device" portal to remotely remove the device from their account *before* performing the factory reset. The latter method sends a server-side command that can invalidate the local lock. All other widely circulated methods, such as using specific button combinations, removing the SIM card, or attempting to bypass the setup wizard through fragmented menu navigation, are generally exploits of temporary vulnerabilities in specific device models or Android versions. These are unreliable, often patched by security updates, and can be ethically questionable if the device is not one's own property.

The implications are significant for both device security and secondary markets. For individual users, it underscores the absolute necessity of remembering their Google account credentials and properly removing accounts via settings before resetting a device they intend to sell or discard. For the industry, FRP has drastically reduced the incentive for smartphone theft, as a locked device becomes a useless brick for thieves, though it has also created challenges for legitimate device refurbishers who must obtain proper proof of ownership from sources. The lock's design makes clear that ownership of an Android device is now inextricably linked to knowledge of the authenticating cloud account, not merely physical possession or the ability to perform a superficial wipe.