Second Hand Macbook Lockout Nightmare

Hey how're you all doing?

I recently purchased a second hand macbook pro, around August, and I was working fine on it until a couple of days ago when I was suddenly locked out.

Reached out to the seller, who I still had a valid 'warranty' with, to help me identify the previous owner, or if I'd been hacked, and he just ghosted and blocked me on whatsapp the morning after.

At this point all I want is to be able to reach the previous owner, maybe Apple can helo, so we can sort this thing out so everyone can get their belongings back and make a statement because the police refuse to help.

Can someone please advise? The macbook in question should be attached? Not really sure how this works yet.