P.S. I have the Flashtool 9.15 version and several C5302 ftf to choose from.
I'd try flashing my Xperia SP C5302 but when it was supposed to be done, I'd try turning on the phone, but it doesn't work. First it started booting with the Xperia and Sony logo, then the animation and kept looping. When I left it alone for hours, now I can't turn it on. it'll only keep flashing red light. when I plug to a charger, it goes to Green, then Red with SONY logo, then back to green. don't know what else to do.