You can see my problem here: https://gbatemp.net/threads/need-help-new3ds-2-1-for-otp.423361/ So, I sent it to modder and the nand can't be detected. Seems like it's not the card reader problem. He tried it with O3DS and success. Then, he discussed it with other modders. And one of them told my modder that he got 4 units too that can't be detected. He checked the first and second unit, and both are Samsung NAND. He forgot the other two. Mine is also Samsung. Is there a solution? My modder told me to replace the motherboard (seems very expensive and hard to find) or made it as cannibal victim (get its parts to repair other console). From the NAND dumping/restore tutorial thread recommended card readers aren't available in my country.