yes i would make a full backup.
for your contacts go to contacts-export contacts-and choose a sd card or your pc.
for your app list,messages,settings use the integrated backup function.
for your emmc take your whole MyDocs and smash it on your pc.
its necessary to make a backup cause there WILL be other issues and to have a backup is always really helpfull.
so after the backup flash your emmc and fiasco and everything will be allright