Hello, Toshiba Satellite U405 - S2856 Screen Problems

Hello, I have a Toshiba Satellite U405 - S2856 which had new screen put in it about 6 months ago because of a busted screen and it worked great ,but then it went out so I put in a new Inverter thinking it was the Inverter , well no luck so I sent the screen back to trade in for a new one and after getting a new one I still had no luck , so I  traded out inverter's  and still no luck . Screen works it just looks dark like the backlight is out ,but there is no way it's brand new . Now on this Toshiba right above the keyboard there's a light that comes on that tells you when the lamp is out and it's on and has been on no matter what I do  ? Now I can hook it up to a big monitor and it works fine also I updated the Bios just for good measure , I even called Toshiba with no luck there either . Only other thing I could think of it might be is if this Laptop has some kind of lamp reset on it , I know some Toshiba's do ,but I don't see one on this machine . Oh, also the screen lights up only for like a split second when the Toshiba logo comes on when you first boot it up and then goes away??  This is just beyond me with what going on ??