Can't login after changing Site Address URL

Looking for a good challenge? Here’s one I truly hope you can help me with.

I have a cPanel account with several addons. The main domain is a WordPress site at https://www.get-business-online.com. The only non-standard thing I’ve done with this site is created a cookieless domain for the uploads directory and redirected that using .htaccess.

While trying to convert this site into a multisite network, WordPress recommends to change the Site Address to get-business-online.com (no www). The documentation also states the WordPress Address must be the same as the Site Address, so I changed them both.

Then, I couldn’t log in.

Notes:

• I know how to get back to the previous setup. What I want is to keep going
• I’ve tried changing only the Site Address, but that already causes this problem.
• I’ve tried changing these settings using various methods suggested here, but to no avail.
• When using the non-www address, the browser is currently being redirected to the www address, but I’m pretty sure this is done by WordPress itself. I can’t find any other place where this redirection occurs.