Thanks Darius,
I flashed my N770 to 2007HE version 4 (year 2008). Then tried a few times. But it still won't work for GPS although I can see the all three lights are flashing. But N770 won't connect to gps. Occasionally, it connected, but it does not show in maemo mapper.
The Navicore works fine in my N770. Please any help will be much appreciated.