How to flash? 1. Run flashtool and click on the flash button 2. Choose "Flash mode", click "OK" 3. From the list on the left select firmware for flashing - BE CAREFUL, if you choose bad firmware you should brick your Xperia! 4. On the right side check "No final verification." If you want to delete your data, check both boxes with "Wipe.." If you want to flash only a part of firmware, use the "Exclude.." option in the middle. Don't use it if you don't know what are you doing! 5. Click "OK" and wait for instructions to connect your phone 6. Turn off your phone. 7. Connect your Xperia while holding the button from the list above. Make sure you're using button which you should use! Don't forget you're in flashmode! When the window disappears, release the button. 8. Wait until flashtool flashes your firmware. If there's not 100% in the progressbar, it's not done! 9. Disconnect your Xperia and turn it on (or make some other changes you want)
You can flash kernels with these extensions: .img, .elf or .sin. For flashing stock kernel use the guide above (for firmware flashing). Remember you need to download kernel file first. Kernels are NOT included in flashtool installation.
1. Run flashtool. 2. Turn off your phone. 3. Connect your Xperia while holding the button for fastboot mode (from the list above) 4. Click on the flash button. Choose "Fastboot mode", click "OK" 5. On the right side click "Select kernel to Flash" and choose your kernel. Click "Open" 6. Move the window right or left to see the log in flashtool window. If it says "OKAY" everything went good. 7. Close the Fastboot Toolbox using button on the right, disconnect your Xperia and turn it on.