Bought a 2019 MacBook Pro with activation lock with proof of purchase, unable to contact previous owner, unable to return, apple refuses to remove lock
What next?
Depending on unstated circumstances beyond anyone else's control
few if any would be willing to attempt to break into the MacBook Pro
(if possible) and remove the Activation Lock.
For all anyone else may know, could be that Mac was stolen. Wiser
choice to determine, before buying, the ownership path is true.
..Apple may choose to help unlock the Locked product only
if they are satisfied the unit passes the proof tests they ask..
(To be able to contact previous owner, who may be honest yet
forgetful of detail, to get them to remove the Activation Lock, is
ideal; however you've had no means to contact them in this.)
• How to remove Activation Lock - Apple Support
https://support.apple.com/en-us/HT201441
If the unit starts up to a 'new owner setup' screen, that is indicative
of correct 'before selling or giving away' instructions were followed.
This item is #7 among 'what to do' before you sell, give away, or trade
in your Mac. And includes how to let a new-user personalize his Mac.
At this point, you cannot do much, as the ownership-path is clouded.