Is there any chance of a miscommunication on his side, that he told his people to look at it and they misunderstood?
Only a fcking moron (Hi Legion!) would tell you to run out right away and get a lawyer. That would cost you money and time, with little chance of recovery. I'd call a legitimate company and have them come out and give an estimate to finish the job. And, then decide what to next.
Look at the bright side, the scammer is already out of time and money, if you haven't given him anything. File a BBB complaint. Give him a 1 star review.
No way, he was there the whole time, a general... not a miscommunication he really was just going to keep going no matter what I was saying. It was surreal.