I will not comment on the hosting service but I have had trouble with them before. Although though I have never used their WP hosting package, I am sure that it would be relatively the same as a normal hosting package (FTP access, DB etc...) .
The Error establishing a database connection is simply a DB/ connection settings issue. I know you may have heard an tried all this before but you should really take this into your own hands at this point. You may find it confusing but worth the time.
Main things first.
- Match the DB settings in the wp-config.php file to the credentials for the DB at godaddy.
- Ensure that the DB is created and accessible.