Devils advocate mode, no doubt I'll get slated by the usual suspects etc but the way I see it from a quick read of that thread:

Doesnt sound like the seller knew anything about the problem when he sold you the box.
He bought the box in good faith, and sold it in good faith thinking it was working.
If its not working now, he's been tucked up himself just as much as you have.

Crap situation, bit unfair on the seller if he bought and sold something in good faith and knew nothing about the issues and now is somehow considered to blame for the fact it doesnt work which he had no way on earth of knowing about? Not his fault at all is it?

I dont see how the seller can be expected to do anything about it other than refer you back to the person he got it from TBH?