Used is not the same as brand new

I work at a small family owned cigar shop that also sells novelties, other tobacco products, and vape supplies. We don't make too much money so we have a no return policy on things like vapes and other stuff that we wont be able to sell back (we don't sell used vape pens because of health issues). Unfortunately sometimes my coworker or owner will make special arrangements with people since we can just send the used vape back to the retailer in case of an issue. I've worked retail for a while and I've decided since if you give an inch they take a mile I'd rather not give anything.

Well apparently we had sold a vape to a customer, and about a week later it stopped working and he called me to return it. As I've said, I follow our All Sales are Final policy and told him sorry for not being able to help him and I'd be happy to give him the manufacturers help number. Well he wasn't taking that, complaining that its our fault his vape stopped working and I was being extremely unhelpful.

Our owner is completely okay with us refusing service to anyone if they're being unreasonable, so I pushed him off onto my coworker who would be in tomorrow saying since it was his sale it was his problem, in those exact words.

The next day my coworker tells me he's allowing the customer to take our last pen and we'll just send back the damaged one. The customer comes in that day, I give him one and the entire time you can tell he has an attitude of "whatever I won, just give me my stuff so I can leave." Whatever, not my problem, take your shit and get out.

A few weeks later we find out he wrote a Yelp review talking about how we're over priced (small mall store what do you expect) and that we wouldn't honor brand new condition. Because apparently used and non sellable equals brand new now