Today I moved the files and database from an old site on another host to a new cPanel site on GoDaddy. I've repointed the DNS of the domain I want to use but it hasn't updated yet, so I've altered my local "hosts" file in Windows until it updates.
After ftp'ing the files over, I saw an error wherein WordPress couldn't connect to the database. I had forgotten to give the database user permissions over the database, so I corrected this and then began seeing 500 errors. If I delete the .htaccess file as some sites recommend, I get 404 errors instead.
I've run some queries to update the domain name, as it is different.
Is there anything else I can try to get around the 500 error? It's very important I keep the database so I can't start anew.
Fixed it - a plugin was causing issues, so I disabled all plugins via PhpMyAdmin (following this) and everything worked fine. Now to work out which plugin was causing issues!