How to Lock the Bootloader on a Samsung Galaxy M12

Understanding Bootloader Locking

• 🔒 Locking the bootloader on your Samsung Galaxy M12 restores security features like FRP lock, preventing unauthorized firmware installations.
• ⚠️ This process will erase all user data and perform a factory reset, similar to unlocking the bootloader.

Preparation Steps

• 📶 Ensure your phone is connected to Wi-Fi before proceeding, as it's necessary for certain steps.
• ☁️ Back up all important data from your phone, as it will be wiped during the process.
• 📧 Sign out of your Google account to avoid potential FRP lock issues after the reset.

Enabling Developer Options and OEM Unlocking

• 👆 To access hidden settings, go to Settings > About phone > Software information and tap the Build number seven times.
• ⚙️ Within Developer options, you will see the OEM unlocking setting. This option is only visible and clickable if connected to Wi-Fi and the bootloader is currently unlocked.

Locking the Bootloader

• 🔌 Turn off your phone, then hold Volume Up and Volume Down simultaneously while plugging in your USB cable connected to a computer.
• ✅ You will see a blue screen; press Volume Up to confirm that you want to lock the bootloader.
• ⏳ The phone will then erase data and restart, which may take approximately 5 minutes.

Post-Lockdown Steps

• 📶 Complete the initial phone setup, connecting to Wi-Fi when prompted or shortly after.
• 🔧 Navigate back to Developer options and disable OEM unlocking to re-enable full security protections.
• 🔄 Restart your phone one final time to ensure all changes are applied.