Are you sure the founder wants to avoid founder’s syndrome?

You don’t say exactly what role the founder had in the governance of the charity or what the bylaw provisions were that were supposed to protect the founder. Presumably, the organization was not a sole member corporation formed with a governance structure designed to protect the interests of the founder and assure the continuation of the mission.  (See Ready Reference Page: “Sole Member Bylaws Can Protect Founder of Nonprofit”) 

But if there were protective provisions in the bylaws, did they require the approval of the founder before being revised?  (They weren’t very protective if they didn’t.) Or was the founder still on the board and not given notice of the proposed changes?  A lawyer familiar with nonprofit law could tell whether there is any clear legal recourse (even though it might be financially infeasible to assert).

Assuming there isn’t legal recourse, the only avenue is political. The founder and those who support him/her would have to seek a change from those currently in power. At this point, it is not likely to be effective, but it may be the only opportunity.