Here you can learn more about the flash tool for Xperia™ devices, which is a desktop application that you can use to flash Sony software on your unlocked Xperia™ device. This is useful if you’ve for example flashed a custom ROM on your device, and want to go change to a standard Sony software. This flash tool can only be used by Xperia™ devices having an unlocked boot loader. Please note that your phone still stays unlocked, and that the warranty may still be voided.
Version Flash Tool (0.9.13.0) https://www.androidfilehost.com/?fid=23203820527943776
Latest Version Flash Tool (0.9.19.10)