Here is a comprehensive guide on what FlashTool is, how that specific version fits in, and how to use it safely.
Developed by Androxyde, FlashTool is an open-source solution that allows users to flash .ftf (Flash Tool Firmware) files onto Xperia devices. It operates using the device's "Flashmode" (usually triggered by holding Volume Down while connecting to a PC). Decoding "flashtool 0691epubl hot" flashtool 0691epubl hot
Inside the FlashTool installation folder, there is a drivers directory. Run the installer and select "Flashmode" and "Fastboot" drivers, along with the drivers for your specific phone model. Here is a comprehensive guide on what FlashTool
When prompted, power off your phone. Hold the Volume Down button and plug in the USB cable. The LED should turn green, indicating Flashmode. how that specific version fits in