Apple

I bought iPhone 14 in June and Sometimes back it started to have some issues (continuous restarting). I came to know that it’s a hardware issue and they will be replacing everything except camera, back and screen. But when I went to take my phone back they said that the issue was persistent and they have given me a brand new phone instead and I was really happy about it as that’s what I initially wanted. What concerns me is, how can I check whether it’s a brand new device or not as they claim. Cause I don’t have any proof for that. They gave me the device in a different kinda box different then the box that we get when we purchase the device. And I checked through net that the model number should start with M for a brand new device but mine was starting from N which they state that it is for replaced devices. And they also mentioned that the serial number is new but serial can also be new for the repaired devices as well. Is there any way where I can check whether it’s a brand new or not?