My partner has just bought the 770 with the sat nav & have only had item a few days, we were using it last night for about 30mins & my partner went to charge it & now when we switch it on the screen is blank. After reading the reviews on amazon where he bought it from, it seems this has happened to another user. The screen lights up when you switch it on, but the nokia logo does not appear & then there are just some lines running down the screen. Can anyone help as it look like we will have to return it to amazon as defective. Many thanks.