Returning it is what OP should do. He paid for a working card, he should not be dealing with firmware flashing. Though I’d try using GPU-Z on a Windows machine to be sure first. Technically you can only be 100 % sure after reading the laser print from the GPU die but that might make returning harder so I wouldn’t bother.
It’s easy to misdetect the card. You just need to flash broken firmware on it that pretends it’s a different card. This is definitely not a 2070 because 1) Powercolor does not make nVidia cards and 2) RTX 2000 GPUs don’t have DVI ports.