Possible computer issue on Supra Launch 21V

My problem originated with what sounded like a starter staying engaged when in neutral. This problem would not occur when engine first started in neutral but when we returned to neutral a second time (kind of a grinding sound). From there the starter failed to engage at all. The boat is presently at a Mastercraft dealer (only dealer even close). I am not sure if I have much faith in them. They started with engine diagnosis, pulling plugs, spinning engine, from there they did diagnosis on electrical, then replaced starter, still no engagement, went back through relays and cannot find any issues. They now want to replace the computer. Anything else they can be missing before having them order a replacement computer?

Thank you.

Something intermittent anymore needs some sound recorded. Were the starter teeth torn up? For safety reasons, I wouldn't expect the function of the starter to be tied into the computer.

I forgot to mention that after the dealer pulled the starter they said it appeared to have water damage.

Sorry, not the starter, but the computer had water damage.