How much of a stretch is it to assume that Sequoia Capital required a new Board before providing funding?
This appears to be a cramdown. If you're desperate when you get an additional VC round, the new investor may insist on 80-95% ownership in exchange for new money, diluting and wiping out the previous investors. Then they reissue new stock or options to the employees to keep them motivated. Since the old board members now own or represent trivial stakes, they resign as part of the funding deal.
I suspect the new executives floated much of the $20M from personal funds (newly enhanced by their nice cashout) and Sequoia is contributing very little beyond its name. Nice strategy.