In the majority of cases, if your TomTom will not start correctly, will not turn off or has stopped responding, a full hardware reset of the unit will solve the problem.
Preparing to Reset Your TomTom
Before resetting your TomTom, check that the battery is in working order by charging for at least two hours. If the charge light does not illuminate during charging, the unit should be returned to the manufacturer for inspection.
Models With a Dedicated Reset Button
Depress the dedicated "Reset" button (Eclipse and Start models only) located on the bottom right of the unit. You will need to use a straightened paper clip (or similar object) and should press and hold the button for up to 15 seconds until it powers down.
Models Without a Dedicated Reset Button
If there is no dedicated "Reset" button (GO, Rider Pro and VIA 110/120/125 models), simply press and hold the "On/Off" button for up to 15 seconds until the device powers down.