ok, I know I'm uber-late in this conversation, and it's all done, but wtf, I feel like saying it. Wouldn't it be possible for the cart to have gotten a static shock either from bad packaging materials, or from bad placement of the cart (ie. on carpet, contact side down)? Static shocks have been known to kill boards. I once recieved a board that was shipped in a box with regular packing penuts that fried it... if the game wasn't a cheap-ass game, I would have been pretty upset, but it was cheap, and I digress... It might be to other people's advantage to track down possible reasons for the board not working when it arrived, when it did work before it left.
I doubt that cleaning the cart did the damage. From how I read it, it sounds like Scott cleaned the cart at least a couple days before attempting to power it up.
I have also dealt with billd420, and know he's a top-notch seller... he likes his fake labels a bit too much, but he does list them as such when he sells them.
morals to my ramblings - static's a bitch... take it to the well and shoot it.