how can I cash a check made out to the estate of my aunt we have joint account the check is for $1700. I have Durable financial power of attorney in F

A Durable Power of Attorney is only effective while the person is alive. If the account you have with your deceased aunt is "joint" rather than "joint with right of survivorship," only half is yours.  The other half belongs to her estate. For her beneficiaries (if there is a Will) or heirs (if there is not) to access that half and the $1700 check, an estate must be opened.  Please see a probate attorney who practices in the county where you aunt died to determine which type of estate administration is required.  You may be able to do a less formal proceeding at lower cost.