He does not understand how to use the product. So can't make the product work. We give help and explanation, but he does not accept any explanation. He will only yell at you and insult you, but he will not use his brain to understand the product. He don't want to read any Instruction, He only hopes that the product suddenly and magically can work on its own，if you cannot give him that，he will call you bad service .

Better not sell，you may eat an unfair bad feedback in the end.