eBay's own money back guarantee only lasts for 30 days. After that, any resposibility rests with the seller.
Depending upon how you paid, it's possible that your payment provider may be able to help.
Otherwise, as your seller is based in China there is nothing you can do, except bin the item and learn from the experience.
Before buying again, do please read Section 2 of the user agreement. eBay even warns buyers that they do not guarantee that items for sale will be safe, legal - or even exist. Would you have bought from a shop that stated this?
Buying from unknown sellers on eBay is NOT like buying from the shops or reputable online retailers. It was your choice to accept the warning and take the risk of buying from this Hong Kong based seller. At least you're lucky that it didn't cause a fire or injury, which has happened to many other buyers.