yo guys, so I sold my wii u to a guy a few days ago, it was hacked with mocha, when he got home, he tried to download mario kart 8 and as it was downloading it got stuck at 19%, said estimated time 99 hours. he left it alone for 4 hours but it didnt change, then he decided to just flat out turn it off, held the power button for 10 secs (i didn't tell him anything about doing this, he did it at his own accord) and now the wii u cant turn on, it freezes midway through the wii u logo, but now he's asking for a refund and that it was apparently my fault for giving him a wii u with a faulty nand chip, for reference my wii u was the mario kart 8 bundle, which came out in may of 2014 (which I told him, but he didn't bother doing any research into the faulty nand chip that these early models are sometimes cursed with) so what do you think, do I owe him a refund for this?