FBA customer return is given an LPN ref, how to find the order?

Hi, here’s the scenario - FBA product, customer buys then returns. Perhaps defective or perhaps just customer damaged, either way unsellable so Amazon sends them back to me. On each product Amazon puts a sticker with a reference number. On mine they are LPNXXXXXXXXX. This number is different for every item and allows you to link that specific return with a specific original order. Somewhere in seller central you can enter this number and it brings up the order, I know this as I did it a few weeks back. However I can’t remember where I did this, any ideas please?

Thanks in advance.