If you region changed your wiiu, it's because your SLC and MLC are different versions. Look for a guide to restore the MLC but make sure you restore the SLC as well as the MLC. It's just another quick download and add it to the install folder.
I can confirm that deleting the MLC again and re flashing it WITH THE SLC TOO fixed the issue. I missed the SLC the first time and I got that error code.