From what you have said, this is not eBay's fault, but the buyer's, as it seems they have mistakenly opened the wrong case.
They must have opened a case for item not received, but eBay's tracking entered the second you buy the Simple Delivery label shows an item has been delivered, albeit just packaging.
The buyer needed to open a case for item damaged in transit, then the buyer would have received a refund paid for by eBay, and you as now, would have kept that payment for the item.
This is the only time though, that a buyer can open another case, ask them to open one now, for item damaged in transit.
@ecj_edw