I have a humminbird 346c di that will not power on. It worked fine last week. The finder is directly connected to the battery. The battery is only used to power the trolling motor and the finder. I have had no problems with the unit until now. I bought it a few years ago new. I have checked the battery and it reads 12.7 on volt meter. I also disconnected the inline fuse and placed the volt meter on the end of the fuse and the negative terminal connection and the volt meter reads 12.7. I changed the fuse and still no power but still reading 12.7 on volt meter. The connections are soldered together. I placed heat shrink over the solder and then wrapped in electrical tape. There are no breaks in the insulation on the wire. The prongs on the power cord are straight and look to be in good condition. The female end on the finder looks to be in good order with no corrosion present. I store the unit inside when not in use. It has not been dropped or damaged. The battery terminals are also clean. Any insight on what might be the problem is greatly appreciated.

Thanks

Tader