It's most probably a blown VRM due to overheating. Those mosfets fail very often.
If the fan desn't spin at all then this is most probably the case.

You can check with a multimeter if you have a short over +/- of the power connector, if you don't
then check if you have a short after the fuses, if you do, visually inspect the VRM mosfets, most often
the failed one is exploded or cracked. Replace the VRM mosfet ( and fuses ) or remove it, most of the card work
well with one missing VRM. Only it will consume a little more power and it may burn the other mosfets in time
due to overloading ( depend on cards )...

If you're not lucky, the other problem could be the GPU failing.. in this case you need a new GPU chip.. probably around 22.. 25usd for the RX570 chip.