You're not gonna be able to scam a scammer lol, no way he will fall for it.
Did you have the funds available in your balance?
Cause if a payment has been completed the only way to "cancel" it and him getting his money back is by him contacting paypal.
That's why you don't use paypal to sell stuff, go OPskins and earn less on the items, but its more safe (even if their bots are hacking so often)