i had this sme issue too. for some reason i wasnt able to see the MDLNA and firefly config tabs. they shoud be under services/plugins/management/MiniDLNA. Try connecting from another browser or PC to the admin page.
Tried different browsers and different PC's - no change
I am also following other threads and it seems this is a common problem that only trial and error and some good luck can resolve so will upgrade to RC1 and retry - keeping fingers crossed.