iPhone 14 Pro is blocked

I bought iphone 14 pro ,,and the owner died. The phone is 1 year closed and I try everything ,I call apple,they told me if the person didn't left me phone in the will they could not help me,the phone is not on black list but noone can tell me where whose bought so I may go there to give me copy of receive. So now I have new phone,worked one month than closed and I can't even change the motherboard becouse noone can tell me for sure that it gonna work. Please if someone had similar experience,what could I do. This photo appears when I insert serial number if iphone have icloud on.

[Edited by Moderator]