Sony NV-U83T Problems After Two years in Storage

I have two U83T gps units that were working perfectly when I put them in storage two years ago. Now both are not working right and both states weak gps reception. The two units have different problems. One is stuck on current position that is 100 miles from where the unit is located and the second unit looks normal, but it tells me to turn left when it is obvious that the correct instruction is to the right. I tried charging the units for 24 hours, pushing the reset button and reloading firmware version 3.02 onto the unit. I know these Sony gps units are outdated, but I really like them and they are good enough for me. I don't know if the problems I'm having is specific to the units I have or if they are common to all gps units regardless of brand and age. Any help would be appreciated.