Reboot the printer.
If that has been done, then clear your web browsers cache or simply use another browser.
It may work by just refreshing the page with either the CTRL or Shift key held (Can'tremember which one does it)
Didn't work for me.
Only just got the printer and there was nothing in the documentation about the Admin password.
Tried 1111 and the serial number but neither worked.
Now I am locked out with Failed login attempt limit has been reached. Access denied.
Is there a way to hard reset the printer.