These are the instructions with Video to flash Sony Xperia Firmware (ftf firmware) using the Xperia Flash Tool on PC.
Step 1: Download and install Sony Xperia USB driver on your computer. if you have already set up the USB driver in your pc then, skip this step.
Step 2: Download and extract Sony Firmware in Your Computer.
Step 3: Download and install Sony mobile Flasher on your pc. if you have already downloaded and installed the Sony mobile Flasher, then skip this step.
Step 4: After Installed Sony Mobile Flasher, Open It (C:drive >FlashTool).
Step 5: Now Sony Mobile Flasher is launched, you will be able to see this screen
Step 6: Now, Click on Flash Button to continue
Step 7: After Click, you will able to see the dialog box. Select Flashmode and Click on OK for Next Option.
7: Now, Select the Load button and Load the Sony Xperia Firmware (ftf file).
Step 8: Now, Turn OFF your Sony Device.
Step 10: Now, Press and Hold Volume Down button and Connect the device to the computer using the USB cable.
Step 11: Once, your Device is connected to the pc, then you’ll be able to see added message in Sony mobile Flasher tool.
Step 12: Now, Flashing will begin automatically and can takes five-10 mins to finish.
Step 13: After complete The Flashing process , disconnect your Phone from the pc and turn it ON.