Did you hack your Wii U yourself? Cause if not, this may not be an easy job at all. If you do have a redNand setup, then FULLY reseting and formatting your SD should do the trick. But if you installed coldboot Haxchi or something else that messes up with booting and sysNand altering, it will brick your console.
Do it at your own risk, specially since we dont know if thats really your issue.
I hacked mine using the reddit tutorial, and realized redNand wasn't necessary. So all i did was format my SD. But than again, i wasnt using CBHC at the time, only Haxchi and Mocha.
--------------------- MERGED ---------------------------
No it can't. Youre not using redNand then.
I really cant help you, and your issue probably will come up on the forums with someone else