I bought a boat this year with the same story except I had the paperwork to back it up. Previous owner did not winterize and Winnisquam Marine replaced the entire engine 40 hours ago for the tune of $6500

I looked at this as a positive since they have a good rep.
When we did the water test we droped it in the water and it started up in 2 seconds. This after sitting all winter. Ran good, sounded good so I bought it.
Since the boat you looked at did not start right up I think you made the right choice to pass. An EFI boat should fire right away IMO.