I see lots of comments on people who do not have a clue in troubleshooting electrical issues. Yes, some can be bad, but fairly simple to cure the problem 99% of the time. Just takes a Volt-ohm meter. This last week at Donner the Garmin and radio would not power up and stay on. Learn to use a meter. Put it on the 20V or so scale and look at a battery, and you will see the voltage. I measured the voltage to the Garmin from the positive terminal to the negative terminal where I hook up the unit. Read 5+ volts, not 12+ volts. Went back to the panel at the transom which supplies power and had same 5V at rear fuse panel. So looked from positive lug to engine ground. 12v. So the positive voltage is good. Missing a real ground to the negative terminal. The ground wire had pulled loose in a butt connector. Replaced the connector And rebook up wire and all is fine. Is not that hard with a little planning and knowledge. Fairly easy to learn how to use a meter. Admitted, I have a lot of knowledge as I fixed main frame computers while earning an Electrical Engineering degree. But buy a decent meter, and learn to use it. My meter was less than $50 from Home Depot. With the ohm meter part you can check if a fuse is really good. Feel free to add to this mini tutorial.