If your Nüvi device won't turn on and has frozen, there are several ways to get it working again.
Option 1) With the device connected to power, hold down the power button for up to 30 seconds. The device should then restart.
Option 2) Connect the device to a computer and wait until the device displays an image (a computer icon appears on the device screen). If the battery is very low, this may take longer. Also be sure to update the device software: WebUpdater