Problems with eBay. Please help?

I put an item. I did not check the item before I put it up. I sold the item. and when I went to get the item to sen it. the item was heavily damaged. I explained to te customer what happend and gave them a full refund. But customer is mad and won't believe me. The customer escalated the problem to costumer support. Can I get in huge trouble? I already gave customer full refund and I actually have proof that item is damaged. What do you think is gonna happen with this problem.?