Didn't they give you the device back with a factory reset settings??
Actually, the only thing which seems to have happened on software side, seems to be that the PIN was now set. Apart from that, it is still on Pixel Dust ROM, which was the same ROM I've been using for many months (since Android 9/Pie). I've not been able to switch back to google ROM, or lock my bootloader because of the data transfer not working.
Meanwhile, I've gotten a mail from the google support team, where they have confirmed the same:
"I would like to confirm that the device will be repaired free of cost and returned with full working condition. Please confirm the details so that I can go ahead and book a B2X ticket for you."
I'm thinking based on this, I can actually go ahead and ask them to book a B2X ticket. I'll also ensure that, I'll take video of the device again, and of the field technician collecting the device, so that I have proof this time also.