You can engage with the founder, describe the problems - as you see them, ask him if he concurs or not. This will produce a number of possible 'forks' to solve the problems with the organization and the people, depending on what portions he agrees/disagrees with. You can engage experienced VC funders/founders to see if there is hope, and to assess the structural or personnel problems. The hope may lie in engaging with the people/processes who are assessed as 'the problem'.

If the problems are quantifiable and people can be educated to see/solve them there is hope. You can be re-capture the start-up thrill and elan that made you all work hard and succeed. Failing this? Find a company that has solved these problems and who has the right people and sell out/merge with them.

This might mean some hard decisions to eliminate the obstructive people with separation shares and agreements to allow them to leave and not want to sue or otherwise harm the company.

Total failure wastes all you and the founder have done to date, so adapt to thrive...