Silvercrest PNA M4310 locked at navigation menu page?

My satnav is locked at the pre-navigation menu page. it as worked fine for 3 months and will bring up a menu page, everything works fine except the navigation option. It will not go any further forward or back from this screen, even when shut off fully.
also, although it has Bluetooth capability, will not pair with my mobile phone even though everything is "on" and pairing password entered. Any advice welcome.