If the board is multi-millionaires, most likely they know what they are doing legally. If you can't afford that roof assessment, perhaps you can't afford an attorney, either.
And I do think there's more to the story here.
If I were in your situation, based on what is said here, and if I couldn't afford an attorney, I would negotiate with the board and see what can be worked out. Perhaps a long-term payment plan for the roof.
But you can probably find an attorney who would take this on for a few thousand dollars or so.
Lic RE Salesperson
New York, NY