2018 60HP Mercury 4 stroke EFI just quit and then no problems???

[Emiliano Valencia]

So I have a mystery. 2020 Tracker pro team 175 txw 2018 60HP Mercury EFI. Started with one key turn out of the water. Yes, muffs on and water flowing out of the pee hole. Ran for 15 minutes no issues. Dropped in the water started up again with one turn. Backed out of the slip, turned and started to throttle down. 3 seconds later dead in the water. Turned over once with another key turn and ran for 3 seconds (no throttle) then died again. Wouldn't turn over anymore. Starter was engaging but engine not turning over. Pulled it out, changed plugs, changed fuel filters (both), new cranking battery, and emptied 8 gallons of fuel. Filled 5 gallons, startron, and can of seafoam. Still would not turn over. Drove it to dealer (hour away) engine is under warranty until 2025. Got a call today boat started right up they were test running it on the lake with no issues. Picking it back up this weekend after another test run. Ok, any ideas what happened?????? Also could the fuel pump be failing but not all the way gone? Serial#1C570272

[EuropeanAM]

Why might I ask are you adding those particular additives to your fuel system? See the FAQ, at the top of the Forum for details/recommendations there.

How much fuel (and how old) were in the boat when it died?

Not completely clear in your post- "turn over" is usually the action of the starter spinning the flywheel. Is that what you are indicating did not happen properly, or perhaps that the starter would just spin and spin, without the engine coming to life....