My favorite GPS Garmin 196 just packed it in. Worked fine for 2 or 3 years and today worked on a short flight and then when I fired up to come up the unit just showed a back light blank screen with a black line through it . The unit was hard wired from a 12v system. The back light would not shut off. I disconnected the unit and removed the batteries and checked them. All ok. Put them back in and now the unit will not come up. Any ideas or suggestions. Thanks Tom