After you enabled the built in Administrator using the command
net user administrator /active:yes in your command prompt, you ought to be able to run that Built in administrator via the Start button.
Left-click on Start then at top of list you see your Account icon. Left click that to open a context menu where the built-in administrator which you enabled is listed. You click that to get to a logon page for this Administrator.
Sample images
When you left click on Start you then see your Account at top of list. Left click that to open a context menu.
After left clicking your account a context menu will appear beneath it with the built in Administrator you just created using that net user administrator /active:yes command. Left click this to get to sign in page for Administrator. The password or pin will be the same as your normal login.
Once you sign in as the Built in Administrator you can remove the Local Administrator account you created that is not working, and then if you choose to, set up a new account with Administrator privileges.
Follow the other instructions I gave earlier from there.