Is blinking red? If yes than definitelly is a hard brick! If not than its not bricked (update your usb drivers)
If you have hard brick like I done on my phone you might read this -> http://forum.xda-developers.com/show....php?t=2682255
i brick it when my phone only allow me to see the sony logo(after root process who dont work and avorted), then I flashtool it with the D5503_14.2.A.1.114.....
pls hellp me :
My phone can't power on , I see red led when I plug it on usb, flashtool don't work now