Serial number

Hello guys,

I bought an used IPhone 11 pro max through Facebook, then I took it to Apple store at Virginia state to fix one of the cameras lens and they told me the IPhone was reported as stolen and I have explained to them and showed them the FB massages between me and the seller though before I buy it I have checked it through Apple website and the IPhone wasn’t reported as stolen and they told me after you bought it he must have reported on the IPhone as stolen so the people at Apple store decided to exchange the IPhone with a new one, but they didn’t give me a box for it which has everything for the phone as serial number.

Yesterday my new IPhone got the screen damaged and I need the serial number so I can fix it how can I get the serial number for it now?? I have the box for the stolen IPhone I can provide if that’s can help !

Thanks.