He bought the console devkit, because he wanted to _play_ with the console and there wasn't a normal unit available. Okay, that was a bad idea and he (obviously?) isn't impressed with what is available right now: Should he still hold on to that expensive unit, or wait for the normal console to appear for a much more reasonable price (and maybe with actual features/'games' he'd be interested in)?
Why would the vendor be at all obliged to let them return the unit in the first place though? Outside of misrepresentation and fraud and things that are not fit for the purposes sold, sellers in general have no obligation at all to take a return. You see retail stores always taking returns, but that's a business decision to stay competitive... they are under no obligation to do so.
If the terms of sale stipulates that you can return it for a refund, or if it was somehow completely misrepresented and then a fraudulent sale by default..... sure.
So if you bought a console dev kit, and it worked as described for the purposes sold (which aren't necessarily the purpose you bought it for) - the vendor is under no obligation to refund you.