Hope you are doing well and sorry for the trouble. As described you are getting the issue with your scanner is not recognized and you have tried troubleshooting the issue without any success.
As you have already tried to remove and reinstall the printer/scanner driver and firmware quite a few time, please make sure that you have the latest version of the driver installed. If not, please remove the the scanner driver and download the latest version of the scanner driver from the manufacturers website and reboot the computer once after installing the updated driver and check.
If it still doesn't work, please try to create a new test user profile with full admin rights on Windows or enable the root account in Mac and try using it there and see if that helps.
Yes, I am using the most updated version of drivers from Brother's site. I have done everything in that "help" page that you linked to. Do you have any pages about how I would "create a new test user profile with full admin rights." ??