I have a necvox overhead unit with dvd built in I...

Question

I think last year I lost one side of my audio right side? So I put a splitter in now this year I turned it on and the audio was real scratchy and only played for like a min then quit all together..I did install a new radio professionally before I fired up because radio would work..this install is on a boat BTW..I'm thinking maybe all my audio went out on the player but dont know...I'm getting good video quality though..anyone help??