You should have taken it to Apple, you would have gotten a new iPhone X right then. It would come in the "coffin case" but those refurb iPhones go through a more rigorous inspection than new iPhones, at least that is what I have heard.
I got a refurb iPhone 5s, because the TouchID on it stopped working but I was way passed the 14 days. It was more like two months or so. I asked Apple if I could have a brand new one, but they would not go for it...figured it was worth a chance to ask, haha.
Anyway, good luck with your iPhone X!