If it's volunteering, argue with your university on that ground. Your SEVIS was terminated because of unautharized EMPLOYMENT, if you can prove what you did was just unpaid volunteering work benefitting the community etc. and no kind of employment was formed(no contract, no salary, ideally not for a privately owned company etc.), I think you do have a fighting chance.
Finding another school to reinstate might not be the ideal choice since a record for Unauthorized Emoloyment won't go well with any colleges.