It looks like you need to rebuild theme files. Follow these steps:
Go to an admin tools of your installation. http://epesi_address/admin/
"Rebuild common cache & default theme" and then "Next".
If this still does not work check your error logs - maybe there is something wrong with permissions in /data directory.
Another way around this problem is:
- perform a clean EPESI 1.5.2 installation on the same server but in separate directory and different database.
- see if everything works.
- if it works - switch in /data/config.php databases and copy any custom/additional modules from your old installation to the new one.
Please make sure to make a backup of your old /data directory and the database.
If none of the above works - please PM me. We will arrange a remote diagnostic session with you (shell access, FTP will be required).