OK so i just did following things
- did a factory reset on my SysNAND OFW 5.1
- then updated my SDCard EMUnand to 8.1.0 using ChoiDujourNX and disabled AutoRCM
- unplugged my SD card, updated SysNAND to 8.1.0 through internet
- with new SysNAND 8.1.0 OFW, created a new account, about to link...