@dcdriver
Very doubt you can update maps for free, as
- hence uses navcore 11xx - which leads us to nav3 or higher version. Till now patching this type of navcore was unsuccessful...
On the other hand - it was successful for Mazda NB1 (navcore 10xxx). But first thing to do - is to get original navcore...
And one more thing - as pe1agp wrote - try to extract your current map from USB drive and extract meta.txt from it... May be it would be worth your efforts?
...and one more - it'll be interesting to get list of files from your USB drive - maybe it contains navcore files?