I got scammed by a buyer

Hello,

We recently had a return for a 49 inch monitor. Upon it arriving, we took it out of the box to ensure it actually had dead pixels in the screen and then issued a refund to the buyer. Flash forward to now, we are attempting to get a refund from our distributor since the item is broken. We noticed that the serial number does not match what we sent the buyer, and then noticed it is a completely different item number. It is a 49 inch monitor, but an older model. I reached out to Amazon by phone, and he said he is sending me a link for a Safe T claim which just brought me to a page on how to file a Safe T claim. Every time I try, it says it is not eligible since the refund was issued on our behalf. Does anyone have any idea how to proceed with this?