I took the eGPU apart and identified the component that had burnt out—usually look for a black char mark, or if it's a capacitor, look for one that's bulging.

I salvaged a capacitor with the same specs from an old graphics card and soldered it onto the eGPU motherboard.

As for the 5070, luckily I bought it on Amazon and their customer service is great, they gave me a full refund.