My father has dementia and my brother had my dad sign over full POA. Since then he paid cash for a house with my fathers retirement and put his name on

the house. He has also purchased a boat with my fathers retirement. There are four children in the family, and my brother is not including any of us in any decisions. He has put my father in memory care 1 week ago. In my parents will everything was to be split four ways after our parents pass on. I purchased a Rolex watch for my father and my brother told me if I want it back, that I need to buy it back. He has abused his priviledges in terms of my fathers financials. In the meantime he has taken all of our parents belongings and has put them in his own house. How can I have my brothers POA revoked and how can an audit be done to see what other financial damage he has done? Thank you!