Sorry to here you are having problems. I’d don’t have a specific recommendation but a few ideas, which you may have thought of already.
New Bedford is a major
commercial fishing port, so that’s your best location for
electronics repair. P’Town is a tourist town and not sure about Plymouth.
Since you are at Pope’s, I would walk across the street to Neimeic
Marine. They are a large
marine engine dealer. While they don’t do electronics
repair, they can probably recommend someone.
You could also search “Marine electronics New Bedford, MA”. I got three hits in New Bedford, but I don’t have experience with any of them so I can’t recommend them.
Good luck