I am posting this hoping to help someone in the future.
I noticed my one year old Jensen Marine stereo radio was turning on and off a bit.
The next time I used it it came on and then was dead for the rest of the day. When I installed it last year I used 14 gauge 2 conductor Marine grade wire direct to the fuse panel. I also used Marine connectors and double heat shrinked all the fittings. Plus I also use Marine grade corrosion proof grease to protect all screw on connectors.
I tested the 12 volt feed terminals that connect directly to the back of the radio and I had 12 volts on the meter. I also hit the reset button on the radio and had nothing. This told me that the radio was shot.
I purchased the same radio and took it down to the marina and put the same connector from the old radio directly in back of the new one.
NOTHING HAPPEND. I thought
WHAT THE? I took both radios home and bench tested the old one and it worked.
Back to the boat I started continuity testing my power wires to the radio and found an open. I traced the pair of wires and found a small opening in the insulation on the positive wire. It was corroded on the inside. In a spot I could not see. It had enough copper to give me a little voltage on my meter but not enough copper left to start up the radio or give me continuity.
I made a repair and everything is okay now. I cannot believe how fast marine grade wire corrodes when a small nik in the wire is exposed to a saltwater environment.