Do you really need to completely format after each failure?Are you sure you did everything ? There is a lot of it.
Format 3ds, properly format sd, check md5 of downloaded firmware, properly set up hax. Just proper format of my SD took me 30minutes (via that program) and i posted it like 5 minutes ago.
Basically i delated everything i had (not much of it really) and started it as if i had new fresh new3ds from eur region.