maybe I'm missing something....
You're not missing something at all. A friend of mine has a family that owns an appliance store, and he said (at his store, this is. I can't speak for any other company) most of the high-price items (computers, TVs, appliances, etc, etc) are tested either by the manufacturer prior to delivery, or in the store prior to sale, to try to prevent DOA products. This means, essentially, if someone has a computer or bigscreen that just "stopped working", the store can say "well, fuck you. We sold you a working product, so exercise your warranty and, if by luck, you get a new, working product back before the end of our return period, you can return it then". This is another reason that stores will send extended "protection plans". They have no intention of taking back your DOA product, and the only way you will get your money back is by sending the product to the "service" broker, who may or may not honor your request. Plus, since less than 10% of users ever actually enact their protection plans, it's a great way to make up for the low margins on high-demand electronics.
We never took back a DOA at OfficeMax when I was there; the person either needed to contact the manufacturer for the standard warranty (in order to replace the product), or enable their MaxAssurance (assuming they bought it) in order to get a refund from the service provider.
If you DO find a store willing to give you a cash return for a non-working product (especially one so expensive), you really do need to find out what information of yours they'll take. For a return this big, I imagine they'll at least take your name and address (off of a photo ID), and possibly another piece of info (driver's license #, DOB, phone #, etc, etc). Retail chains are SLOWLY wising up to shit like this, and tracking big-ticket returns is a really great way to stop shrink. Your information attached to the return is a good way to make sure you don't keep returning "defective" products, and it's also a way to track you down, should they discover the item you returned isn't the item they sold.
Again, the best way you can find out how a store handles returns is to buy some merchandise and then return it. If they won't process your return without your ID, you'd better believe Loss Prevention will have access to that list of returns, along with your sensitive info. If they won't give you cash, but will instead mail a check, then LP will have your name and address.
Side note: unless a store specifically states on their return policy that they only give store credit for returns, you can still get cash, even if you were given a giftcard. FL corporate policy is that we'll always cut someone a check in exchange for their merchandise return giftcard, which is what we'll give for a return with either no receipt, returns after 30 days, or returns without ID. I don't know about any other company, but I'm almost positive that retail div's Loss Prevention investigators don't have any access to FL.com's in-store customer service logs or resolutions; the only thing LP would see is that the gift card the customer was issued is either de-activated, fully redeemed, or just deleted from the database (I don't have access to the gc database, so I'm not sure what info gets shared with investigators when a gc is deactivated by us).