A lawyer got a moderate alzheimers person to sign POWER OF ATTORNEY over to them without the persons knowlege?

They came to his assisted living home and got several of the residents to sign the POA and my Grandfather didn't know what he was signing. He doesn't know about stuff like that. My aunt takes care of all of his business but does not have POA over him. She is on a fixed income herself and hasn't had the money to get it. My Grandfather wants his family to be in charge and make all his decisions and when we tell him what has happened he will be very upset. Is there a law that can overturn this or someone that can help us we don't have the money to hire an attorney. And this is an outrage!