Most people always think it's a power problem, I find more Ground problems most of the time, make sure the main ground wire to the dash is on the battery and it's clean, use a volt meter under the dash using the ground on the fuse block or ground terminal and check for power on the switches, or fuse block if it has one. Some boats have a plug where the harness coming from the back going to the console plugs together and this can get "green" , couple of things to check, but don't trust a test light, digital volt meter is the only way to tell