Default Sony Xperia lt18i (ARC S) does not start, Help

Hi very good day, I have a Sony ARC S .. I installed the CWM to flash a rom .. and I gave her a wipe cache and partition .. and then I went to storage and gave it to reformat the system .. time to turn the phone stays in sony .. can not go to cwm .. try desbrickearlo with flashtool .. but the big problem is when I connect the mobile to the computer .. I press the back button the green light turns on .. I enter .. ok .. flashtool recognizes the phone .. but only after cell latches, and connection with the flashtool is deactivated and is no longer recognized ....
That's the problem, the mobile is turned on in 30 seconds and can not flash it with flashtool
Forgive me for the misspelling, I'm using the google translator ..
Hopefully you can help me friends