now I have an additional question:
is there a simple and idiot proof way to rebuild completely from scratch?
This navigator, originally, was not mine. Now it is, but I'm not sure if all the files in the memory are necessary or not.

I would like to delete all of them (I already did several backups, one before updating to 3490, and other later), connect to the computer, and launch webupdater, so that it will be rebuilt as "virgin" from Garmin (as 3490). I do not think this simple procedure will work, isn't it?

which is the correct procedure for this purpose?