If you paid with a credit card through PayPal here's what you do... I know this because I was just on the other end of this as a seller, but I was in the right, but it doesn't matter. Here's why:
Do a charge back with your cc company. They will send it to PayPal. They will represent the seller but the laws go with your credit card company. Unless he can prove it was perfect you will win no questions asked.
I sold 2 jail broken apple TV 2s at the same time. Different buyers. One no issues the other said it didn't work. It did, I tested it. He sent it back even though the auction was no returns. He tried to re-jail break it not knowing what he was doing He said I misadvertised. He filed with eBay and I won. But PayPal had no grounds for me because no way I could prove his idiocies. No way I could prove he modified it after the fact.
So, do a charge back. Hopefully you used a credit card.