So you have completed a service sub-contract purchase order, invoiced it, not started production and have a production order that had incorrect data set and an inability to resolve this now due to the invoiced purchase order.
Time to get developers involved to try and fix it, because nothing you can do as standard, I believe, will now rectify the on hand. If this is a started order I suggest you post the BOM picking list manually to the correct warehouse (it will not let you post without it) and move on. If you need to rectify all elements you need a developer I would guess.