If Emma says 'The phone is locked' you didnt unlock the bootloader yet. Go to: http://unlockbootloader.sonymobile.com/ and follow instructions for unlocking (needs your IMEI). To check if you CAN unlock the bootloader 1: In your device, open the dialler and enter *#*#7378423#*#* to access the service menu. 2: Tap Service info > Configuration > Rooting Status. If Bootloader unlock allowed says Yes, then you can unlock. If it says No, or if the status is missing, you cannot unlock (read: cant install SFOS)