Please read this if you considering unlocking the boot loader or rooting your phone.
Please note that you may void the warranty of your phone and/or any warranty from your operator if you unlock the boot loader. You should only unlock the boot loader of your phone if you are an advanced user with good knowledge of the technology and risks involved.
For more information go here http://unlockbootloader.sonymobile.com/
Please also note
The Sony Xperia support team will not be able provide any support, related to unlocking the boot loader or rooting your phone.
We also recommend you to read the below blogposts.
Sony Xperia support team
2012-06-24 03:49 PM
Rooting may void your warranty and you are doing it at your own risk
You can't root 4.0.2.a.0.62 as it's difficult
What you could do in order to root is either downgrade to 0.42 or 0.58 and then root it, or flash an older kernel and then root