Unplugging the Wii U during the day-one firmware update might brick the console for good, LA Times film and video game industry journalist Ben Fritz reports on Twitter. Fritz says he unplugged his Wii U 15 minutes into the update, when the progress bar said it would take two hours to finish, and his console is now completely busted. There was no "cancel" option, Fritz says.
A few people on Twitter have chimed in with their own update horror stories, with one saying the connection timed out during the update and another claiming Nintendo support told him to unplug the Wii U for 15 seconds, both scenarios ending with bricks. The Wii U's sizable update will take a while to process, of course expanding the chances of something going wrong. Nintendo has not confirmed the update's actual size.
Nintendo of America warns Wii U owners, "please do not power down or unplug your system while downloading updates. Doing so may cause damage to your Wii U."
In the spirit of Fritz's Twitter avatar, remember: If you unplug your Wii U during a firmware update, you're gonna have a bad time.