I have my friend's wii u and we both have tried to homebrew the thing and failed.

[dirpy_demon]

I tried factory reseting the thingthat also failed, because when I boot into. The wii u it still has the "failed to load payload.elf" message, any advice?

 

[Deleted member 571007]

Most likely one of two things.
One: You put the files in the wrong place, or Two: bad SD Card.
But I'm gonna go ahead and assume that you just put the files in wrong.

I'd just go ahead and recommend that you try to install Tiramisu as it's the base-standard at this point. You can find the guide to do so here.