My friend got sick and ended up in the hospital. She fell and broke her back, while there. She was put in a nursing home for rehab, while there she suddenly became unresponsive. She ended up in the hospital again only to recover and go back to the nursing home. Within a little over an hour at the home she became unresponsive again and was sent back to the hospital.
I would go to a lawyer with documentation proving why this person is not a good power of attorney. It can be revoked, but you need legal help.
How is it that you wish to intervene? do you wish to help her go, or keep her on life support? IN such questions I don't see a better solution than consulting with a lawyer. IF you can't afford a lawyer, look up 'legal aid' in your area. This will point you to folks who can better answer your question.
If she does recover her senses, have her create a living will document or otherwise give you POA so that if this comes up again you have more recourse
You state this is a friend - is it a family member that holds the POA? Or are family members involved in the decision to stop any life support?
I guess what I am wondering is how does the family feel about the decision made by the holder of the POA?
You do know that all control of anything that has to do with your ill friend by the holder of the POA will stop (cease to exist) upon the death of the person?
Only an attorney can really help with what you are asking but I believe you should also be talking to her family about their wishes.
To fight it, it will become a court matter, so you will need to start with getting attorney.