So I recently had this issue. I couldn't play Hyrule Warriors due to an error in an update download. This only happened with Hyrule Warriors though.
What I ended up having to do is go into my system settings and turn off automatic downloads. I went into my data and deleted the corrupted data. I reset my wireless connection. I then restarted my Wii U and tried started the game. The download was larger and completed and installed perfectly.
It might be worth a shot.