What can I do when this past year I have been denied any contact with mom by younger sibling who lived with mom?

mom had four strokes the last one really did her in, she has dementia. The past year i have been denied any contact with mom by younger sibling who lived with mom. I called elder abuse because i did not know if mom was alive or dead and brother was harassing me with tests of a hundred or more a day. they were also threatening ones too, because he said i was not helping with her care. I had POA of her bills and banking he had POA of her medical needs. I tried to do everything i could about protecting her money so it would be there for her care. Brother is very good at spending her money but every thing i did i was always shut down like my POA meant nothing and i was not being told much about mom at all. She is now assigned a state guardian and is in a nursing home I still am only told what they would say to the man on the street, she is well and happy. I wish there was a way i could be told more as i live in another state far from mom. I have been through hell with the stress and resentment and now on medical care of my own. I refuse to let the siblings make me feel guilty for living away.