Media Markt Sent Me a Used PC as a New

I bought an All-in-One PC from Mediamarkt.com in Turkey. Instead of a new PC, they sent me a used or opened one. I noticed a white blemish or spot on the charger while configuring the system. When I tried to register my system on the Lenovo website, I received the message, "This system was already registered in April 2023." Next, I attempted to initiate an exchange or return request, but the Mediamarkt.com website returned an error message, preventing me from proceeding with the request. I've attached documents pertaining to all of these processes.