If the buyer opens a case for item not as described it's all automated, no human contact.
You can contact eBay Customer Services, and I recommend trying only very first thing in the morning when the lines first open at 8 a.m. as there's more chance of Dublin answering, to put your side forward . Be aware, eBay cannot see this item, and even Brand new items can break down and become faulty so not fit for purpose.
It's a hard one to predict an outcome when a case for this is opened, it may be worth getting the item back, and fully refunding the buyer, you need to pay for that fully tracked retunr postage, and do you still have a warranty for this item? To try and claim a refund from the manufacturer?
Any loss of postage costs you can add this amount to the starting prices of other items, so you're not out of pocket.
@loftclearout74