What do i do… seller keeps denying refund requests

I ordered a pretty expensive fpv drone a while back, it arrived with its camera completely broken, and i wanted to get a full or partial refund by returning the drone, but no matter how many times i accept Aliexpresses proposal, the seller denies it, and insists they want to send a replacement camera and asking me to cancel the request, although i do not know how to fix it myself. its been a constant back and forth for more than a month now… how do j can aliexpress or the seller to accept the request?