Sorry if I wasn't clear (or maybe gave way too much information). I don't believe I have access to a 6.4.1 installer, so my initial approach was to try moving the public_html directory & the MySQL dump to a server and deploying it that way. I actually did this both on my production server as well as a local MAMP server running php 5.4.45. Nothing was merged on either site. They're all the original files and data and, since no installers were used, everything was configured by hand.
Although both of these sites seem to work on the frontend, I can't actually login to either one using the credentials from the live site. The strange thing is, the mysql dump is from the live site so I'm not sure what the issue is there. Regardless, I created yet another account with a fresh install of 6.5.5 and then I attempted to merge the data on that site — which obviously, was a bad idea.
As for the 6.5.5 approach you suggested, I can definitely try that. I do have a 6.5.5 installer, but didn't realize there was an upgrade script. So I will give that a shot. Thank you so much.
