Check your manual. Pages 40 to 46. There is a page that refer to diagnosis of starting issues. There is also a schematic. It mentions loose connections etc. Check all your connections and examine all the wiring for signs of corrosion and arcing (melted insulation etc). It also mentions what to do about induced water damage.
I think this could be a duplicate post concerning the same boat regarding an electrical issue....then I've answered both questions.