My brother is POA and his girlfriend is caregiver to my mother, she has dementia. They won't let me see my mother. What can I do?

I have a 90 year old mother who has alz/dem. She made my older brother POA a few years ago. All the account that had my name on them are gone. I don't know where they are, but he does. I can't reach my mother, she lives 60 miles from me and is in her home which goes to my brother upon her death. My brother won't return my calls, letters. I don't know if mom is home, in SNL, etc. I'm afraid I won't see her again. I have an attorney for elder law, probate etc. They say they can't do anything since my brother is dodging my calls. Is there any agency that could help me. My mothers lawyer called mine wanting me to sign the last of her stocks over and I have refused unless I talk to her. That was 4 weeks ago. I had the local police do a welfare check, they told me she said, let her talk to my lawyer! She would never say or do this if she was in her right mind! Can anyone help me?

Everybody paid off or bribed or promised a carrot on a stick. Most follow the money