I think I bought a stolen iPhone 8 plus

I bought my first IPhone, an iPhone 8 plus, in Ghana last year December. After updating the OS, it is requesting for the password of the icloud account attached to the phone. I went back to Ghana for work this January and asked the seller what happened. He said I shouldn't have updated the OS. That I needed to unlock it. And that after unlocking I shouldn't update. I felt it was awkward and later concluded it could have been stolen.

Please, I don't mind losing the $245 I spent to buy it. I just want my peace of mind by returning it to the rightful owner. Kindly spread the news until it gets to the owner.

Thanks

[Edited by Moderator]