What do I do if I signed a waiver for an additional 3 months but my attorney hasn’t done anything since the previous waiver?

My brother, 16, signed a waiver after he was told by his CAA that he had to sign it or the judge will make him sign it. He was also told that in order for him to get out of juvenile detention center, he had to blame on our brother, whom his CAA was told by an unknown source that committed the crime. He is being charged with murder and according to previous lawyer he was arrested because witness who was later found to be unreliable because he was a heroin addict and was under the influence at the time of questioning. Why is he being held there if this attorney thinks it’s our other brother who did it?