I got scammed :D

Went to buy a supposed brand new Nintendo Switch OLED from a Seller through Facebook marketplace. He said it was sealed and brand new, with promises of everything inside. He didn't want to sell it through Facebook itself since he didn't have to time for the money to come in, he needed it immediately since "the lights were gonna going to get cut out". Believing him, I asked to send video proof of the switch being inside, but he mischievously showed everything else besides the console and controllers itself. We agreed that I would pay for the product, and he would send it over through FedEx with paying for shipping of $16.10. Waited two days for the product to ship but when it arrived, ultimately, the console, controllers and power cord were nowhere to be seen with only the Dock, Grip, HDMI cord and controller wrists wraps inside the box. In complete shock, I grabbed my phone and tried contacting the seller, saying that I didn't receive the product. He claims that that's all he received from GameStop when he purchased it from them, but that is a lie.I asked for the money back in exchange for me to ship it back to him, but he responded saying "Not happening" leading with a block on all communications. I'm currently in dispute with Cash app, Bank of America and Facebook about the scam. I even went to GameStop to see what I could do with the leftover product and the guy said that everything left inside is deemed worthless since the actual console, controllers or power cord aren't present. I even mentioned to the GameStop employee that he said that the switch wasn't included in the box, and he said that is a complete lie and that goes against everything GameStop stands upon. I was ripped off 266 dollars worth of money which wasn't easy for me to get and im simply asking for my money back. What should I do?