1996 Ski Nautique - Electrical Power Loss Upon Ignition

[Houston7831]

Hi All, I'm having a very confusing issue. I have a 1996 Ski Nautique with the Throttle Body PCM Chevy 5.7/350 I was out on the water late last year and was returning to the boat launch when I heard a "pop" at the rear of the engine and had complete electrical power loss. Got the boat home and didn't start to mess with it until a couple of weeks ago. Due to several other things going on I replaced the following parts. Battery (Battery tender said it was bad) 50amp push breaker at the rear of the engine Starter relay Had the starter rebuilt. The problem I am having now is when I try to turn the key over for ignition, I immediately lose power to the dash and the back of the engine has a little "click". I checked the push breaker for continuity and to see if it was blown and it was not. Power returns between 5-20 minutes later but when I try to turn the key over, the same thing happens. I'm confused as to why I would intermittently lose power for a period of time and then for it to come back on later just to repeat the issue. My next thought is to replace the ignition switch. If anyone has a wiring diagram for this boat that would be awesome, But I can't seem to find one. Does anyone have any suggestions? Thanks!

1996 Ski Nautique PCM 350