Navigator IV looks like a zumo 660 but it not react like zumo to pre-boot mode. Navigator IV have the mini-usb under the battery cover and the cover have an magnet inside. With the cover removed the device after start have the "close battery door" message on screen. When connect the usb cable the device start but PC did't recognize the connected device.
I try all possibilities to put in pre-boot mode but I have no results. Only react of PC with very short time is when the cable is connected and I push the power button for more then 5 seconds.
I think the only way to recover the device is to find the exact procedure to put in pre-boot. Also I don't know where to find the RGN file for this model.

Anyway, many thanks for all advices.