eBay's money back guarantee, which is not a warranty, only applies in the first thirty days after receipt of the item.
Manufacturer's warranties typically only apply if you purchase the item from an authorized dealer; check with the manufacturer to see what your options are.
A warranty is only as good as the reputation of whoever offers it. A claim of a two year warranty made by a random seller on eBay is not worth much. Neither you nor eBay can force the seller to honor the warranty if the seller disappears or ignores you.
You may have some protection from PayPal or your payment method; PayPal and many credit cards may offer up to six months protection for your purchases, though PayPal has limited "not as described" returns to thirty days. After your credit card protection expires, you have few options.
