Charging problem: My navman won't charge?

Hi, the charger itself is fine: we tested it in the shop this morning. There seems to be a problem with the devise itself ie the chargers power won't connect to the battery from inside the devise ; so no power. ??dead battery, but don't think so. Looks more like the internal connection from the charger to the computer is faulty. Can you advise ? Navman F series sv00026 canada 310
Thank you. Jane