I had traded an iPhone with someone using an app called "OfferUp." I checked the IMEI and everything to make sure it was clean(not stolen or iPhone locked), which it was. We traded and everything was fine. I tried updating my phone to iOS 11, and now my phone says "There's a problem with your iPhone. This phone can't be activated for service. Please contact your carrier or AppleCare." I went to Apple and they said the phone was reported stolen?!
I checked the serial number and it says the phone was purchased on JANUARY 1, 1985… The phone is 33 years old? But its the iPhone 7… Was the phone actually stolen? I'm so lost.
The phone was working fine when I had traded with the person.
Read more: Online serial number checker for iPhone says my iPhone 7 was made in 1985?!