I just received my Zumo 550 back from Garmin, I was hoping that they might send me a Zumo 660 as some on here had said that they had got one. I will just have to settle for the Zumo 550.
The reason I was interested was that the same thing happened to the 550 of a friend of mine and nothing I
could do would get it to turn on. He sent it back to Garmin hoping the €110 would net him a 660, instead
he got a 550 in pristine looking condition, funny thing was it had a load of waypoints from it's previous owner !!!!
If I were you I'd try ringing them again, I was told the same thing a few months ago by one "service advisor" and was told to post the unit to them by another. Worth a shot, but if all else fails DON'T bin it, the LCD/Digitizer, the battery and the unit case is worth something.