Flashing from 5.0.2 to 4.4.2, xperia t2 ultra doesnt turn on...

Hello,

I tried to downgrade my xperia t2 ultra from Android 5.0 to 4.4.2 and after following the spets my smartphone died....

When i try to turn it on, it vibrate only.
It detects as a Sony ericsson on sony pc companion.
When charging the red led keeps turning on and off...

How can i fix this :'( i am so sad