Problem with ebay buyer? -

I am having a problem with a buyer. I sold a phone what was in perfect condidion. The buyer send me few E-mails while the auction time asking if I could do a buy it now trnasaction for him, which I didn t do.He won the auction and I shipped the phone right away to the addres provided. I also added an insurance , since the buyer didnt ask for it but I wanted to make sure the phone will arrive.The buyer got the phone and he claims that a botton doesnt work. I do NOT understand why that does not work cause the phone was in a great condition and I knwo for fact everything worked correctly. I dont know what to do now. I dont want that phone back if it does not work cause this is not what I send. I also said in my listing that I dont accept returns, just because I am in the middle of moving.Please help me. I am a costumer for 5 years with a 100% positive feedback. I am always honest and I dont want to lose my good fedback!

well, as i see it your only options are 1) do not accept the return, 2) accept the return and refund money, 3) have buyer contact post office to claim insurance money or 4) give partial refund