Replace the Battery it's the cheapest way out
I have had two problems with GPSs. The first was a battery problem similar to yours. It was an ICOM made by Panasonic (no longer made), and it just quit working. ICOM wouldn't touch it because it was made by Panasonic and panasonic wouldn't touch it because it carried the ICOM name. The local repair shops wouldn't touch it because (for similar reasons) they couldn't get a schematic. In frustration and with nothing to lose I tackled the job myself, and found the battery buried between two circuit boards, and I replaced it. It has worked fine ever since. My other experience was with my Magellan DX5000, it worked just fine and I had it interfaced with a Digital Beacon Receiver, Radar, Fluxgate Compass, and my Auto Pilot, so I wanted to keep it. Unfortunately the LED screen gradually washed out in the sun to the point that I couldn't read it, and I asked Magellan to repair it. No deal-- They told me to go out and buy another (newer) GPS and I did, but I was so ticked off at them that you can bet that it wasn't a MagellaI ended up with a Standard Horizon WAAS Color GPS/Chartplotter that does everything I need.
