If you used Delete Title in step 1 or could not findNintendo eShop or 0004001000022900 in Titles.
You need to delete the ticket because the Nintendo CDN server doesn't allow you to fix system titles if you present fake/spoofed tickets.
3. System Settings → Other Settings → System Update.
This should redownload a (clean) copy of eShop.
Take it from someone who messes with NAND stuff a lot: quit whatever experiments you're doing to the 3DS firmware while you're still ahead of yourself.
While 3DS hacking and custom firmware has come a long way in fixing all sorts of software issues, some things are better left alone because short of having a backed up (full) NAND image, there are certain super softbricks that are not fixable.