I did a cursory internet search and not much turned up. A full replacement main board may not be easy to come by. That leaves you with a handful of options: (1) Take a roll of the dice and see if you can find a used one on eBay (I wouldn’t recommend this unless you have good relations with the seller) (2) Contact Shark/Ninja and ask if they have the parts and get a quote/see if they will sell or give you one (3) See if your ninja is still under warranty and file a claim (4) Since the main board is relatively simple, determine which component has gone bad and replace it (i.e. resistors, capacitors, etc.) I don’t recommend performing option number 4 unless you are very comfortable with electronics. Best of luck! And remember to be safe when working with electricity and electric components. Here is a guide for using a multi meter to test components on the PCB Here is a guide for testing different PCB components.
Does this only happen on the initial fill? Or does it happen rinse cycles too? Where is the leak coming from? Sometimes, the rubber seals on the water inlet hoses don’t work well or the hoses aren’t tight/snug. The fill cycle pulls water from the inlet hoses and sometimes (due to water pressure), the jolt caused by this can cause hoses to loosen over time. My first recommendation is to check the inlet hoses, and verify that they are tight and still serviceable. After that, start a cycle (on hot and cold temp so both hoses pull water) and check for leaks. The leak persists, allow it to run and search for the source. However, the hoses are often times the culprit. Hope this helps.
Just to add to what jayeff said. First and foremost, try to be as specific as possible so that we can help you with better information. What cables are you using? What kind of display/TV are you connecting to? Gamecubes have two different video outputs : RCA (Analog - Yellow, Red, White) & Component (Digital - Green, Blue, Red) RCA is the most common connector (component cables were not manufactured in as high numbers and thus, aren’t common) RCA uses a single cable video signal (the yellow one) and two audio inputs for left/right (white, red) Component cables use a THREE cable video signal (green, blue, red) so all three cables have to plugged in to give correct signal. TVs with component connections only do not work with RCA connections (to be fair, in the past, a few would allow the green connector on the TV to also be used as yellow for RCA, but that is rare) and vice versa. If you are using an display with only HDMI ports, I recommend an adapter such as this one on amazon and if video issues continue,...