Lol. This is refurbishment, nothing new. I have seen it happening in front of me many times.
Refurbishments are all about reconditioning, making an old or damaged phone look and work like new.
It could be just casing change, battery change, lcd or other faulty parts replaced, or even be running everything non oem replaceable parts inside.
If you are a noob in used phones, there is 75%+ chance that you are going to ripped off while buying used flagships, especially imported kits.