Unable to complete the batch whose Req was accidently closed instead of cancelling it

We are OPM OSP enabled organization. We have a batch that was created, materials were issued into it and the product was yielded. The product was accidently associated with a OSP step which resulted in creation of requisition. Users realized that the batch does not need a requisition and wanted to cancel it, but they accidently Finally closed it. So now, we are unable to complete the batch as we are getting the error message that the 'PO/Req associated with the batch is still open' and also Lot costing is completing in a warning because the product lot was yielded