This seems like an example of a scam not working on eBay.
It did work, because even though I got my money back and returned the phone, the mechanics of the complaints process - and his immediate opening of an issue against me - meant that I was never able to warn others of his dishonesty.
This is a seller that had “100% perfect” transactions.
Won't save them, eBay will close their account after a couple of disputes like yours.