How do I know if someone canceled my POA?

My mother and I have POA over my grandma. However, my mom's sister had my mom removed by having my grandma sign a paper. My grandma said she did not know what she was signing at the time. Now my mom does not have POA over my grandma but I may still. Unfortunately we do not know if my aunt made herself grandmas poa when she had my mom removed. If we ask, she will not answer us. But we need to know so we can find out what our next step should be.