Update: I contacted the seller on Friday evening via Whatsapp. We went through a series of troubleshooting steps and I provided visuals of me unpacking the card, describing the problem and going through the troubleshooting process as described by the seller. On Sunday, he agreed to return and I received the refund in full on Monday. For whatever reason the return order hadn't been created until today, and I offered to create the shipment from my side free of cost. In any case, he has sent me the shipping label for the return, and I have it packed in the original packaging, ready to go.
Even if it didn't go as I had hoped, I will still be giving a positive reputation to the seller because he was willing to stand by the warranty/refund that he had mentioned in the listing originally. That's more integrity to his sale than most retailers can claim. I was willing to wait for the refund until after he had received the card back, but he refunded me the amount even before that, which was very upstanding of him.
The problem: When installed in the PCIe slot and 6+2 PSU power plugged in, the PC wouldn't power on (not responsive to the power button). Take the 6+2 out, and it powers on, but doesn't boot (obviously). This happens only with the 2060, and not my previous card, and it persisted through different configurations, and even an Intel test bench that I set up later. This isolated the video card as the issue, and comparing symptoms leads me to believe that there is a short in the card which trips the OCP in the PSU, and hence doesn't power on. The outer packaging didn't have any signs of damage or tampering. The physical condition of the card was also as expected. No scratches or dents anywhere. The backplate was never removed and the heatsink shroud is spotless.
Edit: The card is on it's way back, as of now.