Until now, Sony Ericsson refused the requests from the Android community to allow developers to unlock the boot loader of their phones, since there was no secure technical solution in place to support this. In addition, the boot loader could not be shared since that would violate important business agreements with many of the company's partners, such as operator customers and developers who want to protect their apps and games from being ripped from the secure area in the phones.
The solution is currently under development by Sony Ericsson, which will allow developers to unlock the boot loader for certain releases of 2011 Xperia phones, such as Xperia arc, Xperia neo, Xperia pro and Xperia PLAY. However, this will only be possible for certain releases of the phones. Basically, your phone has to fulfill a number of requirements. For example, you can't unlock the boot loader if you have a SIM lock protected phone.
There are other requirements as well, depending on your market and the original configuration of your phone. The only way to determine if you can unlock the boot loader for your phone is to connect your phone to the Fastboot tool in the Android SDK. If your phone can connect to Fastboot, the boot loader can be unlocked. For earlier products such as the Xperia X10, Sony Ericsson cannot allow the boot loader to be unlocked due to technical and legal reasons.
Also, note that you may void the warranty of your phone if you unlock the boot loader. Additionally, due to the modified phone software, Sony Ericsson?s repair network may not be able to properly test and repair your phone according to its normal procedures. Consequently, if Sony Ericsson does perform a warranty repair, Sony Ericsson may charge users a handling fee for any additional incurred costs due to the modification of the software.
If you unlock the boot loader and then flash a custom unsigned ROM to your phone, the custom unsigned ROM will not have gone through the tests that Sony Ericsson runs for each phone and software version that they release. Because of that, the custom unsigned ROM might not work properly on your phone. Certain functions may cease to work, and the performance of the device might not be ideal.
Sony Ericsson recommends that standard users NOT unlock the boot loader, as it is not needed. However, the company hopes that this is a useful service for advanced developers.