TomTom One IQ Routes not starting

[germane]

Hi, I have a TomTom ONE IQ Routes /140 - 2GB which will no longer start. The last time it was used it was switched on successfully but quickly turned itself off, since which time pressing the power button does nothing. Pressing and holding the power button for about 30 seconds to reset the unit achieves nothing. Plugging the unit in to the pc results in the power/charging light being on, but the unit still won't respond to the power button being pressed.
Any help would be gratefully received.

 

[dhn]

How long did you keep the unit plugged into the computer? Keep it there for a good 3-4 hours and then see........