This buyer will purchase a certain amount of products at one time. We think that he only needs to use these things temporarily, and there is no long-term use requirement. After he uses these products to complete his use, he will contact you to say that some products are not working.
The seller was willing to help him from the very beginning and told him to count how many of them has problems and they could help replace them. The buyer could not provide an answer.
Finally, the buyer said that as long as there has some of them has problem, he just want to think that all have problems, he must return for full refund, and threaten the seller to complain about them.

Did you see，this is an obvious scam case, even he don't want to test all items, he still not answer exact how many is "some of"

Do not sell to this buyer.