Xperia devices bootloader unlock relock

This guide is for anyone having trouble
unlockin bootloader in xperia devices and this for advanced users only
note: unlocking bootloader voids your
warranty but hey you can relock your
bootloader and your phone is under warranty
once again
Unlock bl give lot of troubles bootloop etc
Firstly you must know youre firmware version and that is combind with flash tool
**open the dialler
and enter *#*#7378423#*#* to access
the service menu. In your device, tap Service
info >
Configuration > Rooting Status . If
Bootloader unlock allowed says Yes,
then you can continue unlocking your phone..
if its no then please stop and don't try the
next steps
1.find youre imei number and go to xperia official site and find youre bl unlock code
2.Download flash tool
3.install it
4.go to the instalation folder and drivers folder then instal flash tool drivers app and launch it
5.now select flashmode drivers,fastboot drivers,search youre 4n model and instal drivers
6.launch flash tool app and click blu button then flash tool show instructions for you for conect youre xperia via data cable in flash mode
7.then enter bl unlock code and then you can unlock or relock youre bootloader
8.finished :-)
I cant tell all devices required firmware version thats youres work.unmatchng firmwares give bootloop :-D
Downloads flashtool from here
Find bl unlock code from here
If boot loop comng then flash ftf file using flash tool or use sony update service from here these make youre phone to original state