Brink should add a note to the tutorial.
I moved an SSD with Windows 10 Home (OEM) from the computer it was licensed for to a new Optiplex 3040 that was licensed for Windows 10 Pro (OEM) and obviously the activation failed since the hardware was changed. Entering the Windows 10 Pro (OEM) key that was embedded in the Optiplex 3040 failed as well. So I found this forum and entered the Windows 10 Pro retail key that Simrick provided, which allowed the OS to do an Edition upgrade, then I just changed the key to the embedded key and activation succeeded!
Thank you, @simrick
You referring to this section of the tut?
Yep, that's not a retail key per se - it's a generic/default/public key used for edition upgrades, and, as the tut says, it will upgrade but not activate your OS. But you had everything under control with the key on the new system. Glad to hear it worked for you, just like it's supposed to! Thanks for posting to let us know. Cheers!