Should I probate my mother's estate?

This response is intended as general information only and no attorney-client relationship is being formed.   Generally, "powers of attorney" are revoked after the death of the grantor. Actions taken after the death of the grantor generally can be set aside. However since you knew the grantor was deceased and used the power of attorney, equitable remedies may prevent you from benefitting from the transaction. The re-financed loan may be held to be enforceable under equitable principles of unjust enrichment or other equitable remedies. Many factors have to be considered in such a case. There is no "one" answer. If your mother's only assets was her home, title may have passed to you subject to paying off the mortgage. However other possibilities exist. The original mortgage may have converted the joint tenancy into a tenancy in common. Without reading all the documents involved, no definite answer can be given. Also consider, that with the help of a lawyer, the Mortgage Company may be willing to reach some lower settlement of the unpaid mortgage.