This buyer receives item, then emails claiming the item is problematic, then proceeds to tell you that he will leave negative feedback if you do not make it right for him. He has left 90 negative an neutral feedbacks for sellers out of 277 transaction in the last year. As a seller you have a 30% chance of getting a negative. Block this guy, and if you have received negative from him, report him. eBay needs to know about buyers like this.