Storm Media Limited Sent me a defective product and now they won't replace it or refund my money

The product I bought online does not work. When I notified the seller they asked to buy new batteries and to make a video showing when the batteries are opened from the package, installed and that the product does not work. I sent it. They replied back to use brand new batteries with FLAT & SMOOTH negative side. I sent them a picture of the batteries I used and they told me that the product does not work with the “Energizer” brand. I contacted Paypal with the issue but I had no luck. They sent me an email that they favored the seller because they provided me with enough information for the product. I am not spending any more money on additional batteries. I already complied with their request of proof. The batteries I used are AAA batteries as the product indicated and the ones I used have a flat surface on the negative side. They are saying that the product does not work with “Energizer” brand. To buy and use 2 new more brands and send video. I just want to return the product and that they replace it with a new one that works or that they give my money back. I have never had such a bad experience returning a product. The product does not have anything written on the box or instructions that indicate not to use with that brand.