https://en.wikipedia.org/wiki/Wolf,_goat_and_cabbage_problem
There may be limits to what you can do with a modern ferry, but it would be nice that if when everything else fails, it just revert back to being a "dumb ferry". So you'd be able to use it, but only in fair weather, or with more staff, something like that. Then you yank out the broken bit and install a replacement. While knowing very little about ferries, I suspect it's the integration of systems that makes repairs difficult.
<https://duckduckgo.com/?q=fogo+change+island+ferry+site%3A.c...>
Upshot / TL;DR:
The new ferry, the MV Veteran, was built by a Dutch firm, and at least one set of repairs required it being returned across the Atlantic to Europe for an engine refit. Substitute service had been provided by, variously, a sister ship, the Galatea, the older ferry that Veteran and Galatea replaced, MV Earl W. Winsor, as well as a fourth ship, MV Legionnaire, fixed-wing and heliocoptor aircraft, the latter at standard sea-based ferry rates.
This 2017 article discusses then-current issues as well as a five-year history of troubled reliability:
<https://www.cbc.ca/news/canada/newfoundland-labrador/mv-vete...>