Was out on a charter yesterday and I noticed that the radio had turned itself off at somepoint. It was getting dark so I turned on the Navigation lights and nothing. The master switch, which usually has a red light when it's "on," was completely dark. The gauges were working (i.e. Speedo, tilt/trim, rpm) but the lights, radio, master switch, and bilge were not. Made it home safely and charged the batteries overnight. They were actually fine. Motor ran the whole time so I assumed it was the other battery. However, its fully charged and the switches still do not light up.
Where should I start looking for the issue?