A friend of mine brought an xperia phone to me, I decided to help him upgrade it. The label behind has lt18i written on it, so I used the ftf for lt18i with flash tool to upgrade it. It all went well, but phone has refused to go pass the xperia boot screen, I even downgraded back to gb and it won't go pass the Sony Ericsson screen. I just saw something strange on the phone, it has an external antena between the usb port and volume control buttons. Is this the xperia arc s? And what firmware should i use to flash it