Hey, you're not forever stuck there. It happened to me yesterday, same stuff going on. I sent my Wii U to Nintendo, telling them that when I boot the Wii U,just after the "Wii U" screen (like 3 secs after) it crashes and I can't even access Home Menu.
If you want to recover your Wii U, do what I did : ask Nintendo to repair your Wii U, telling them it's bricked. DON'T SAY YOU HAVE TRIED INSTALLING HAXCHI/HOMEBREW because they can deny.
Just say you tried to boot up the Wii U and error code popped-up and you kept trying a lot of times and same thing happened.
(Btw, if you they ask you "Is it your first time getting something repaired by us?" answer "Yes, I've never had any problems before.")