Disconnect the BM5 from mains for SEVERAL minutes
- in the meantime check all connections between BM5 <> BS5 and the external conections as well
- restore power, let the system boot and check if everything is OK
- if not, reboot again and select "recovery" at the boot screen
- and let the system recover (you'll lose your favorites/playlists and have to reconfig the system again)
- after recovery trigger a manual SW-Update
- if you don't get a boot screen - contact dealer / service