Meet Morris Robinson. At 30, in finally attempting to sing professionally, he tried out for the chorus of “Aida” at the Boston Lyric Opera, the biggest company in New England. A week later, the music director handed him music for a solo role, accompanied by a plea: ‘Please don’t screw it up’. “A lot of the purists, they don’t believe my story,” Robinson said. “They don’t believe it until they witness it themselves.”