I just got a TomTom One -- at first the screen would stay on until disconnected from power, then after a few seconds it would go black and start again when I touched the screen. But now it started turning off after a couple of minutes even when still connected to the power, yet the voice is still on (I can hear it talking when the screen is black). Anyone know how I can go back to how it was originally? I even tried to reset it but didn't work.