What happens when adult protective services finds out brother is guilty of financial exploitation of his mother, after siblings turn him in?

Even if the victim will not or cannot (dementia) etc. if there is sufficient proof and documentation then go back to the first and second items above.

He gets the option to pay it back or go to prison (financials).
He gets probation or prison time for the physical/mental abuse.
Often the victim will not testify against him, in which case he goes free.