SYMPTOM: The radio keeps beeping and it says “Check Plotter” on the display.
These symptoms indicate that the blue wire has been accidentally grounded. The blue wire is an alarm input, which is typically connected to a chart plotter. If the blue wire is grounded then it will trigger an alarm on the marine radio.
Check the cables on the radio – one of the cables has a blue wire for the alarm input. Make sure that the blue wire does not touch anything.