When you say member do you mean member of the Board of Directors? Or does the organization have actual members? In either case, the first step for challenging the Board is to review the bylaws and take steps based on what they say - assuming the comply with the law. If the steps you want to take are nt outlined in the Bylaws you should review state law to see what it says about the situation.
If the Board refuses to follow the Bylaws, there are really two viable options: 1. is to report the organization to the PA Attorney General's Office - http://micurl.com/AktcCug or 2. if you have some sort of standing you can file a suit in State court seeking an injunction to prevent the Board from doing what it is doing.
Since you have not provided any detail as to what the Board has done it is not possible to give a realistic assessment as to whether either of these approaches would work or be effective. Generally, the Courts do not like to interfere with the inner deliberations of a organization, but Bylaws are a contract and the Court, in the end, will enforce contracts. The Attorney General reviews all complaints, but whether they will do anything is highly dependent on what is being done by the Board.