Our new Indie Games subforum is now open for business in G&T. Our rules have been updated and given their own forum. They are nice, and there may be new ones that you didn't know about! Go and check it out, you might land a code for a free game. I've never owned an HD TV before so im new to this.Also make sure the Wii U is outputting at the same resolution as the TV.If you're developing an indie game and want to post about it, follow these directions.
So it should be stickied but anyway, hope you get your system back working.
This issue's caused by turning off the Wii U during the middle of a massive update—reported 5 GB according to GTTV's Geoff Keighley—required to access all of the Wii U's online content.
Considering that this update would take most anywhere from an hour to five hours to download, it's understandable as to why some users would apply the update, see that it's taking longer than expected to apply, and decide to ignore the warnings of not shutting off their console during an update.
For now, it doesn't seem like there's a way to reverse the issue.
According to Venturebeat, the issue isn't something that Nintendo can resolve remotely.
But in Nintendo's case, "off" really means something like "on standby." If users expect the Nintendo Wii to be truly off, they need to pull the power plug -- assuming there isn't a battery foiling that tactic.