Blacklisted Samsung phone

So there's this random phone I found quite a bit ago and decided to try and turn it on for once and it started up with the recovery mode screen and I factory reset it, after it finishes resetting it starts up as like a new phone then it says to sign in with the PIN Which I obviously don't know since it's a random phone I found and when I try to get it unlocked on the at&t website by putting in the IMEI it tells me the phone is apparently blacklisted/reported lost or stolen and I was wondering if I can get this phone unblacklisted and or unlocked in some way because I really want to be able to use the phone