TLDR: GPU had risen in price, sent for RMA within warranty with easily repairable problem but was destroyed by manufacturer instead, according to the retailer. I was preparing to sue the retailer to get broken GPU back to have it fixed by third party repair shop. Manufacturer eventually gave me a replacement GPU after media attention. Make sure you specify you want your repairable product back if you send something for RMA that has risen in price!
Story: I bought an Gigabyte RTX 4090 from a major Dutch retailer that came with 3 year warranty. 2 years later the power connector melted. (the new 12vhpwr connector).
I used a Cablemod angled power connector, one that was officially recalled, which I missed. So I was prepared for a denied warranty claim. I contacted Cablemod first and they said they would refund a repair at a third party repair shop if retailer and gigabyte denied my RMA request. That was nice of them.
I did not consider that sending a GPU for RMA might mean Gigabyte would "destroy" it and the retailer would refuse to give me the damaged GPU back instead of just denying RMA and sending me the broken GPU back.
Retailer claimed they sent it to gigabyte and gigabyte destroyed it. Best they could do was give me a full refund, which didn't cover the cost of a new or secondhand 4090 with risen prices. Obviously, they have an incentive to repair the card, try to get me to leave with a refund and then sell the refurbished card for 50% profit.
I asked for my broken GPU back, they said take the money or leave it. I threatened to sue and wrote a post on a Dutch tech forum describing the process. The site picked up on it and wrote an article about it: https://tweakers.net/reviews/14700/geld-terug-is-ineens-een-slechte-deal-je-garantierechten-bij-stijgende-prijzen.html
This gained traction and Gigabyte customer relations contacted me. They offered me a replacement card of different type that was slightly used by them in a test bench. I accepted and my issue was solved.
But I would have had to sue the retailer to get my property back in case this wasn't picked up in the media. So the warning is: if you send a product for RMA that you think is easily repairable that has risen in price, make it very clear that in case they want to deny you RMA or destroy it, you want that broken product back to fix it yourself.
Gigabyte European customer relations said they changed their processes based on this case and that they had destroyed the card in order to have a quicker turnover rate. They will now not do this anymore for products that have risen in value and price. They were nice and helpful and I hope this helps other people out.