Flashtool 0.9.23.2

A prompt will ask you to choose a boot mode. Select and click OK.

Flashtool will display a prompt asking you to connect your phone. Turn off your Sony Xperia completely. Press and hold the button. Flashtool 0.9.23.2

The official Flashtool website (androxyde.github.io) now hosts newer versions, but you can find archived copies of on reputable developer forums like XDA-Developers. Always verify the SHA-256 checksum to avoid malware. A prompt will ask you to choose a boot mode

If your Xperia device is stuck on the boot logo (soft-bricked) or suffers from severe system crashes, this tool can completely rewrite the Android operating system to factory conditions. Turn off your Sony Xperia completely

Beyond this, the core capabilities of Flashtool 0.9.23.2 included:

: If the program hangs while preparing files, close Flashtool, end its task in Task Manager, delete the contents of the \.flashTool\firmwares\prepared folder, and try again.