I've owned my Nuvi 2798LMT for approximately 9 months. Worked fine until yesterday. Suddenly while driving, the screen went blank but the GPS continued to give voice commands. When unplugged from the car cigarette lighter, the display came on in battery mode. The cord's red light is illuminated when plugged in. Works fine in battery-only mode, display blanks out when plugged into power. Cycled power numerous times. Used different cigarette plug, etc. When plugged into laptop via USB, display is very dim, but readable. Any one have a suggestion on how to fix this problem?