Backup your µSD to a Backup folder on your PC BEFORE upgrading to a new Kernel

Format your µSD with the Panasonic SD Formatter 3.1
Use these options :
FORMAT TYPE - FULL (OverWrite)
FORMAT SIZE ADJUSTMENT - ON

PRIMARY Kernel :
Extract these files from R4SDHC YSMenu folder and copy to root of your µSD :

_PATCH folder
_system_ folder
Games folder
TTMenu folder
_DS_MENU.DAT
_DS_MENU.INI
_DS_MENU.SYS
DEFAULT.nds
r4dldi.dat

Boots automatically to YSMenu.