Please remember, each time you lock or unlock the bootloader all of your data is wiped..
Any Root will also be gone. You will also be needing your current stock firmware.
Scenario 1. Your phone is rooted with Magisk.
- Go into Developers options and check OEM options, the switch must be ON (to the right). If it isn’t turn it ON.
- Turn off your phone.
- Press and hold the Vol up or Bixby and Volume-down button, then connect with USB to your computer. (The cable shouldn’t be connected until after you press the buttons).
- Within seconds of USB connection the Download screen will appear.
- You will see 3 optiions, choose and Long press volume up (Device Unlock Mode) and hold button
- Until you see the 2 options at bottom of screen. Choose and hold volume up (Lock Bootloader) until screen goes off.
- Then the logo screen will briefly apppear, before it flicks back to the Download screen with the words ‘VBMETA: Error verifying vbmeta image etc’ at the top, as the image below.
- This is all good so far. Leave the phone exactly as it is with this screen showing and make sure the phone is still connected to the computer.
- On your computer, fire up Odin3_v3.13.1, you can leave the Reboot option in Odin ticked.
- Locate your stock firmware on your computer and put the 4 file parts (BL, AP. CP and CSC) into Odin.
- Let Odin finish.
- The phone will reboot ready for setup.
- The Unlocked bootloader warning screen will be gone.
Scenario 2. Your phone has been rooted but isn’t now, and the greyed out OEM switch is ON
Easy, turn off your phone and proceed from the 2nd paragraph of Scenario 1.
Scenario 3 Your phone has been rooted but isn’t now, and the greyed out OEM switch is OFF
Sorry, but in this situation, you are going to have to root your phone with Magisk as the OEM switch will only be available when rooted.
When rooted, proceed as Scenario 1.
Scenario 4 Your phone has never been rooted. i.e. you unlocked the bootloader but never proceeded to root the phone
Turn off your phone and proceed from the 2nd paragraph of Scenario 1.