I am running Windows 10 Professional. Very recently I experienced a failing motherboard. So I replace with a new one.Upon boot I have the “Activate Windows” watermark and cannot remove it.
Major hardware changes require reactivation.
You can activate over phone.
Press Windows key + R then type: slui.exe 4 and hit the Enter key.
Select your ‘Country’ from the list.
Choose the ‘Phone Activation’ option and follow on-screen instructions.