002-0121 - restricted from Online services

[MatthewL246_PNID]

Based on this post, having a swapped friend code seed can also cause this error. Consider trying this as well if none of the other steps worked.

My 3ds console seems to be eternally banned [002-0121]

I think you already tried this, but maybe you could try some of the other methods in the Restore LFCS script?