Can a lost Iphone 6 be somehow restored and used after its reported lost?

Hypothetical scenario: David finds an iphone 6 on the street. Although he could be the better man and figure out a way to return it, he is in need of cash and goes by the quote "Finders keepers losers weepers" and decided to keep it.

Is there any way to hack/restore an iphone 6 so it can be used?

If it's locked and has Find My iPhone enabled on it then it's basically useless, and any pawn shop that has any sense will check that and refuse to buy it if it's locked as such.

Plus, the phone's IMEI/ESN will be blacklisted if the owner reports it lost/stolen to the carrier. It IS technically possible to change an IMEI but it's not easy and it's fraudulent as hell.

If David is ready to spend some to get it to work, sure David can use the phone. If David needs help with the issue, he can mail me for more info.