in my 2015 Fiat 500L I have the Continental FIAT 312 VP2 ECE DAB NAV 5" UConnect unit running TomTom maps software. All other functions on unit work find, and NAV has worked fine until last week, but now on pressing Nav the TomTom log displays with the red dots to show progress during load, but just hangs on this feature. I've tried to find a hard reset for the unit but no joy. I've removed the unit so no power but on reinstall security code not required and unit still hangs in NAV mode. so now thinking what software/firmware updates can be done, but as I can't get into NAV menu to find current versions. I can get into engineering menu but no reset / reboot options there. Any tips to restore Nav function?