The buyer returned the item using a fictitious return reason.

[xvendoomx]

Hello, tell me what to do, I sold a phone, new in factory packaging, without a return option.
After the buyer bought it, he apparently did not like it and decided to return it using a fictitious reason for return.
When I received the phone back and checked it, I found that there was no problem with the phone. But now the phone is in damaged packaging, already used and now I can not sell it as new.
When returning, eBay did not offer me any options to dispute the return. What should I do? Is this normal on eBay? I searched in the help, but there are a million links and no specific answers.

[jacbarcollectibles]

If the buyer used the "Item not as described" reason for the return then this is automatically accepted by eBay and you have no choice but to allow the return and give a full refund on return or allow the buyer to keep the item and make a full refund.  Unfortunately the fact that the item is now used and in damaged packaging bears no weight with eBay.  They will say that this is a cost of doing business and will offer no help.