Well I first off tried removing the htaccess file.
I've traced the correct version of revo from the database so now I have the correct version to overwrite the existing one.
The server is CentOS 6.4 with a plesk panel.
Running PHP 5.3.3, with php.ini configurable settings.
Have full access to the Apache modules
here is an error log excerpt:-
mod_fcgid: stderr: PHP Fatal error: require_once(): Failed opening required '/var/www/vhosts/mywebsite.com/httpdocs/core/xpdo/xpdo.class.php' (include_path='.:') in /var/www/vhosts/mywebsite.com/httpdocs/core/model/modx/modx.class.php on line 41