How to Lock Bootloader and Enable Protection Features on Samsung Galaxy A51 5G

Preparing Your Samsung Galaxy A51 5G

• 💡 Ensure you are connected to Wi-Fi before proceeding.
• 🔍 To check the bootloader status, navigate to Settings > About phone > Software information and tap the Build number seven times to enable Developer Options.
• ⚠️ In Developer Options, you should see OEM unlocking enabled and grayed out, indicating the bootloader is currently unlocked.

Data Backup and Account Removal

• 💾 Back up all your data as the process will erase your phone.
• 🗑️ It is recommended to delete your Google account from the device to avoid re-entry during setup. Go to Settings > Accounts and backup > Manage accounts, select your Google account, and click Remove.

Locking the Bootloader

• 🔌 Power off your phone by holding the power and volume down buttons, then selecting Power off.
• 💻 Connect your phone to a computer using a USB cable.
• ⬆️ Simultaneously press and hold the Volume Up and Volume Down buttons, then plug in the USB cable.
• 🔒 On the screen that appears, press and hold Volume Up to confirm the bootloader lock.
• ⏳ The phone will restart and undergo a reset, which may take approximately 5 minutes.

Post-Lockdown Setup and Protection Restoration

• ⚙️ After the reset, set up your phone. Connecting to Wi-Fi later can speed up this process.
• 🔓 Once setup is complete, go back to Settings > Developer options.
• 🚫 Disable OEM unlocking to restore protection features like FRP (Factory Reset Protection).
• 🔄 To finalize, press and hold the power and volume down buttons, then click Restart.