well this would seem to be a common fault as mine also acts in the exact same way i just keep trying the power button and the reset button and eventually it comes on , its not often i use mine so very disapointed as these are not cheap to buy and unfortunatly the gaurantea is now up
dave
October 2009
I had the same problem, green light when on charge but would not switch on, so I looked under the TomTom where it connects to the holder and there is a reset button.
Use a pin to press the reset button and it should start up again - mine did.