That has happended to me, it broke everything on the Wii U side. Decaffeinator did nothing (that was the tool that broke the Vwii in the first place... it is a long story... don't ask). I recommend using Vwii nand restorer with tiramisu.

use vwii Decaffeinator once you are done with that boot into aroma while holding plus and add the update folder MAKE SURE AROMA IS UPDATED OR YOU WILL BRICK THE WII U then just update hope i helped!

i turned on a vwii mod and the same thing happened to me so i deactivated the mod and it works now