Always inspect the item prior to paying someone. Did you not ask the seller for serial number, model number and other model specific details? Where did you meet the seller? If you met at a public place or coffee shop than see if that business has cameras installed so once you file police report (if you do), they have evidence of transaction. I am sorry you had to go through to this.
In that case, yes they might not be able to help. I hope it wasn’t a highly priced item. If it was a cheaper item - i would say use it as a lesson learned and move on. For future reference always use Offerup as method of payment if you are getting an item shipped and for local sales - meet at police station, public places. Inspect the item to your satisfaction - i always tell my buyers to open and inspect before payment. It takes lot of efforts to stay at 5+ star rating. Lastly, always look for reviews and truyoumemeber certification - 99% chance they will not be a scammer.