Seller asked to close Return request. What should i do?

[smart-pal-supermarket]

I got an item from ebay seller and it was defective one. he has put his listing it is brand new, but it is used one. so i request him to refund me. he tried to cheat me and i opend a return requst. so now he agrees to send 50 % money back and keep the item with me. so he asks me to close the case to refund. i know if i close the case, i will not be able to re open it. so what should i do. if i close it he is able to go away without refunding me. what to do? please help.