PS:
I trust that you tried this command already: /opt/fedora-ds/slapd-servername/start-slapd
If typing in a terminal window, there might some helpful output.
But, the /fedora-ds/admin-serv/log/ states
As said before, it is my experience that - in case the underlaying directory server is not running - that should better be rectified first before taking care of any errors from the admin server.
Good luck!
Wolf