Sony Ericsson is the first Android device manufacturer which officially offered bootloader unlocking on select Xperia devices. Sony Ericsson Xperia Arc is one of these devices whose bootloader can be unlocked officially through Sony Ericsson. However there is a certain glitch that follows official unlocked bootloaders on these devices. There are many users who claimed device brick after attempting to update over the air. And one common feature with all these devices was unlocked bootloader! Well we don’t really know when Sony Ericsson will start pushing a fix for these unfortunate devices, but XDA member Jerpelea has released a homebrewed fix that should work just fine.
In order to deploy this fix to revive your bricked Sony Ericsson Xperia Arc due to OTA update, you will need to download Flashtool. Flash Tool for Xperia devices is basically an all in one solution for Xepria devices to root the phone, install custom recovery, flash custom update.zip etc.
In order to unbrick your Sony Ericsson Xperia Arc phone, you will first need to download this FlashTool package containing the tool and Unbrick FOTA essentials. After you have downloaded the zip file, extract the contents of this archive to a location of your choice, connect your phone. launch FlashTool.exe and click Flash on top navigation bar. Once you click the Flash button, you will be presented with .sin and .ta files. Select the files in appropriate order to flash and then follow onscreen instructions. In case you are stuck or need more information, then head to the official XDA thread. In order to save your bootloader unlocked device from bricking in the future, always decline OTA update messages unless Sony Ericsson is out with an official fix for this.