FOP2 does not touch any of your GUI configuration files at all and in any way. Whatever you did to break the GUI is probably not related to FOP2 itself.
One thing you might want to check is that your admin manager password was not changed in /etc/asterisk/manager.conf. If you change that password, and forget to change it also on your GUI configuration files (like /etc/amportal.conf or similar), then things will work quite badly.
Best regards,
