It's always best to backup your microSD to a folder called Backup on your PC before upgrading to a new firmware version.

Then format your microSD with the Panasonic SD Formatter and use these options :
FORMAT TYPE - FULL (Erase ON)
FORMAT SIZE ADJUSTMENT - ON


IF YOU WANT TO USE THIS FIRMWARE AS YOUR PRIMARY FIRMWARE :

Copy your M3Real/M3iZero firmware back to your microSD, then extract the files from new firmware and copy/replace the following to your microSD :
System folder
TTMenu folder
SRESET.DAT
YSMenu.nds

Copy usrcheat.dat to TTMenu folder

Then create a folder called Games on your microSD and put all your games and saves into that folder 



IF YOU WANT TO USE THIS FIRMWARE AS YOUR SECONDARY FIRMWARE :

Copy your M3Real/M3iZero firmware back to your microSD, then extract the files from new firmware and copy the following to your microSD :
TTMenu folder
SRESET.DAT
YSMenu.nds

Copy usrcheat.dat to TTMenu folder

Then create a folder called Games on your microSD and put all your games and saves into that folder 

Boot your carts firmware, then load YSMenu.nds