First make full backup of your device with Windows explorer and store on a safe place on your pc.
Then go to folder Navigon\Map and exchange the old files with the simulair new ones.
Spoiler: image
With this files it have to work for The Netherlands.
If this works you can add the Mapfiles(countries) of your choice.
Then (if preferred) go to te map Navigon\poi and add new poi files.
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