How to prevent returning to supplier once the inovice is validated?

Hi ,

There is one retrun to supplier transaction after the invoice is validataed.

The logistics did not inform finance dept. and fin proceed to make the payment.

I checked the PO & AP user guide, it seems that changing the PO status to final close may prevent the action against PO.

Can PO become final close automatically?

Can I reopen for a final closed PO? Thank you.

Best Regards,

Anna