My uncle is legal guardian and POA of my disabled brother. His caseworker says he needs a lawyer.

My uncle has POA and legal guardian of my brother and refuses to sign it over. My uncle gives him only $50 a month and keeps the remainder of his $1150 for himself. My brother is being abused and forced to live off of junk food. He hasn't had a new pair of shoes since high school. He is 30 years old with the mind of a 13 year old. Can someone please help me get him out of there? My uncle has hit him with a hammer and mentally and emotionally abuses him as well. Please help my brother. I live in Shamokin, PA and my brother lives in Holtwood, PA. Who should I contact and what should I do? The caseworker says she can't change POA or legal guardian without my uncle's consent.