How can i fix my gps signal on my tomtom start 2?

Hi i recently brought the start 2 and had no problems for about 3 weeks. But now i cant get a gps signal, the devise also stops responding to touch, and switches its self off, or gets stuck!! Ive tried the reset button for 15 seconds and going outside but no joy. Has anyone got any other ideas, or had the same trouble as me pls help...Thanks!!|||Have you charged the battery recently?