Does the NPO have a grievance or problem resolution process? Most do. Check the bylaws. Depending in what kind of non-profit, It's also possible that there is no legal remedy outside the organizations own policing that can be taken.
The reason the previous attorney likely refused to get specific is that it is unethical and possibly a serious code of conduct violation for an attorney to give legal advice without knowing all the facts, which cannot be reduced to an email forum. In addition answering a question too specifically may give rise to the existence of an attorney-client relationship. There are some heavy responsibilities for attorneys that go along with such a relationship.
NOT LEGAL ADVICE. FOR EDUCATION AND INFORMATION ONLY. Mr. Rafter is licensed to practice before the state and federal courts in Virginia. There is no implied or actual attorney-client relationship arising from this education exchange. You should speak with an attorney licensed in your state, to whom you have provided all the facts before you take steps that may impact your legal rights. Mr. Rafter is under no obligation to answer subsequent emails or phone calls related to this matter.
If this is not yet in litigation, you're looking for a lawyer who handles corporate law. If it is in litigation you are looking for a lawyer who handles commercial litigation and it would be helpful for that lawyer to have some track record in corporate matters.