Although I want to introduce you to a psychological counselor, I doubt whether your brother will cooperate with the treatment. You'd better talk to your counselor friends, or you can attend some psychological workshops or something. In short, don't let him feel that he is treated as a patient.
In addition, if you really want to treat him, you can take more interesting treatment methods such as sand table, or warmer ways such as narration.
Good luck! ~PS: Everyone comes from adolescence, and many things are understandable! ~ Come on! ~