If he had no mysql then i belive that the installation would not even start.. as mysql is required for ISPConfig..
What kind of Joomla problems? What errors? Did you enter all data correctly? You created database for joomla in ISPConfig?
Do a new installation again of ISPConfig and report back if you can get ISPConfig page or not.. Maybe you missed something while reinstalling..
Edit: btw, you didn't post the whole log of that file.. just first 'page'