mobile

i have m8x and its in costume rom mod
i want to return in stock and get ota...
s-on
unlock
and costume recovery is be
my build number was 4.16.709.4...latest version
help me to get stock mod...
i try to flash nandroid backup and flash stock recovery....and download ota but after download update and install in recovery my cell phone is be dark and not coming ..i had to flash costume rom again
thanx for your help...