If you used Simple Delivery and an item is received damaged in transit, buyer should open a case citing this damage, then eBay refund the buyer and you, the seller, get to keep the payment.
If you refunded yourself, there's no way now to be reimbursed by eBay, you can try Evri, I understand the process there is not straightforward.
if you wish to sell on eBay familiarise yourself how Simple Delivery works, as eBay protect sellers against items lost or damaged in the post, by refunding themselves, and you keep payouts for those items.
This explains how SD works:
https://www.ebay.co.uk/sellercentre/postage/simple-delivery?mkevt=1&mkpid=2&emsid=0&mkcid=8&bu=43952...
@1471piper