Ok, I will try to use as many files as I can, from other devices backup I made in the past.
Garmin Express and Webupdater, dont have more updates for it, so i think thats the way.
Until now, the only thing I have added, is Basemap v5.01 (from my Nuvi 3490lmt)

Sorry but I dont know what NV is, or how to backup.
Do you also want me to reset device ?
Maybe I should make a backup of favorites etc. with Garmin Express before doing so ?