To all those that wondered what happened, the conf file was missing a sub directory.
$modx_manager_path= ’/path/to/site/root/manager/’;
should have been
$modx_manager_path= ’/path/to/site/root/public_html/manager/’;
I wonder if instead of the page dying silently, there could be something that is displayed instead? Something like, "file not found, please check your modx_manager_path"?