Good news, My Wii U no longer has that error code. you see a few months ago my 3DS Broke down so my older brother sent it in for repair, then after I picked it up a couple days ago, I found that I got a refurbished one. So all I had to do was retrieve my NNID and link it to that 3DS (Fortunately, the saved data I had on my SD Card was still intact so I didn't have to worry about losing any saved data) then the next thing I knew I was able to access the Wii U Eshop! I am so relieved!