The only way you can get POA is if your uncle gives it to you. He can only do this if he has sufficient mental capacity to execute the form. Whether he does or not is something you should have an attorney help you determine. If he has capacity, once the form is signed, the attorney should provide notice to the former agent that the prior power has been revoked. Notice should also be sent to anyone having the prior document.
If he lacks sufficient capacity, then your only recourse is to go to the probate court and seek appointment as his guardian and conservator. You will need an attorney for that process, as well.
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