See you are getting plenty of advice now ... that's good ...
Hostgator should have some sort of panel (cPanel) that you can log into. Probably by IP address with a port.
cPanel's File Browser will allow at least poking around ... finding where things are located ... and it's probably what you used to edit config.php. There is a version.php file that contains version of Moodle.
Let's not confuse questions about what you use to connect to server with what operating system the server is running. OS makes a difference. cPanel should show something about that.
Also ... cPanel might have a 'Terminal' icon ... that's command line. If it doesn't, contact hostgator help desk and ask if that could be installed.
Can customer share one login/pass with you? Can they login?
IF so, you could make that user temp admin and use that account to login by adding a line to config.php.
$CFG->siteadmins='IDNUMBEROFACCOUNT';
Should be able to login with that account then and see the 'Site Admin Menu'.
'SoS', Ken