follow the Tutorial step by step
6.turn off your phone and when Flashtool shows pop up window, connect phone to PC with holding volume down button
04/004/2015 10:04:41 - INFO - Device connected with USB debugging on
04/004/2015 10:04:42 - INFO - Connected device : Sony Xperia E1 Dual
04/004/2015 10:04:42 - INFO - Installed version of busybox : N/A
04/004/2015 10:04:42 - INFO - Android version : 4.4.2 / kernel version : 3.4.0-perf / Build number : 20.1.B.2.15
04/005/2015 10:05:07 - INFO - Selected Bundle for Sony Xperia E1 Dual (D2104). FW release : 20.1.B.2.15. Customization : Brazil
04/005/2015 10:05:07 - INFO - Preparing files for flashing
.....
04/006/2015 10:06:08 - INFO - Processing of cache.sin finished.
04/006/2015 10:06:09 - INFO - Ending flash session
04/006/2015 10:06:09 - INFO - Flashing finished.
04/006/2015 10:06:09 - INFO - Please unplug and start your phone
04/006/2015 10:06:09 - INFO - For flashtool, Unknown Sources and Debugging must be checked in phone settings
at the beginning on this
in the end I believe this off