You can't be sure, of course, that it's the same one you sold them. But unless you made some kind of promise about it working, they probably can't do anything anyway. And unless you sold it for a lot of money, it probably isn't even worth their time and effort to sue you over it anyway. But if they do, they will have to be able to prove that it wasn't working and you knew that fact before you sold it to them and lied about it, or otherwise misrepresented it in some way or gave them some kind of promise or warranty that you didn't live up to. Otherwise, it's a waste of their time and money to even file a claim. I wouldn't worry too much about it.
This answer is for general purposes only and does not establish an attorney-client relationship. The law in your state may differ and your best answer will always come from a local attorney that you meet with privately. For a Free Online 50 State National List of Consumer Law Lawyers, click on this link (http://tinyurl.com/79ku5jx) and find one near you
So long as you did not provide a warranty to the buyer, you have very little to worry about. If the buyer sued you in magistrate/small claims court, the buyer still would have to prove either that you gave the buyer a warranty or you knowingly concealed from the buyer that the console was not in working order when sold. Further (and just for clarity so that you have some additional comfort engaging in non-warranty private sale transactions), Georgia's lemon law only applies to "new "automobile purchases, so it would not impose any obligation on you/your son as the seller of the console.