Try just pasting the hostname into your browser. If you get a login prompt that's good. Try the user name and passwords. This might help you narrow down which piece of info is bad.
If you are changing database passwords as you are making attempts, make sure you are waiting long enough after changing it in the panel. If the panel says wait 10-15 minutes then wait 30, it does take a little longer than the estimate for the panel bot to actually change password sometimes.
Make sure you don't have an extra space from pasting before a closing quote too.