Thanks, unfortunately I cannot get into pree-boot mode.
I did the following:
1. Power OFF your Nuvi. / 2. Press and keep holding the most left upper corner of the LCD screen / 3. Power ON your Nuvi but DON NOT release your finger either from Power button nor from LCD screen (keep both pressed until the procedure ends) / 4. You will notice Nuvi boots in Pre-Boot mode. Now quickly connect your USB cable.

The PC recognizes the device for about 4 seconds and than not anymore.
The screen on the nuvi does not change at all, still the Garmin logo but nothing else.