Buyer requests return after buying a clearly stated faulty product?

[888terri]

Hi I listed a laptop in the "For parts and not working" section. I clearly stated the problem with the laptop. The buyer contacted me prior to buying it requesting a Buy It Now option, I put one up and he immediately  brought it. Then I had to open an unpaid item dispute to get him to make payment. I sent the laptop he received it. He then messaged twice telling me the problem was different to what he thought and has now requested a return (I have stated no returns). I have never had to work through one of these before. What is my best option - as I don't feel I should have to accept the return or give him a refund. He asked no other questions prior to purchase, which I happily would have answered. Thanks for any help.