You can open up a dispute. If the seller said it works, and it doesn't, you will win the dispute.
I buy a ton of stuff on ebay, too, and I've had things not work twice.Go figure both were from Hong Kong. I've quit buying from overseas, though electronics are SO much cheaper there.
Anyway, both happily refunded my money or sent a replacement. They know if you open up a dispute that you will win on something not working.
If you can, make a video of it. The more evidence you have to present, the more likely you are to win a dispute.....but, most will give your money back the minute you open a dispute.
I would try directly asking him for a refund(they pay return shipping), and if he says no, then tell him you are opening a dispute.
You did pay with paypal, right?