Chosen Solution
When I turn on my Toshiba Satellite L300D it starts up fine but screen has no back light. I know the screen is working as if you strain you can see it very faintly. Also if its closed & on, you can push down lightly on it & it lights up - but only for a short while.
My first thought was that it sounded like an inverter problem. The only thing that stumped me was that it works when you apply pressure. I believe that the best way of truly determining what it needs is by disassembling it ( check here for instruction) and take a good look at the ribbon cables going to your LCD. I suspect that one of the wires broke and that is why it works when you move/push it. Would probably easier to replace it than to check it for continuity. If the cable is okay your best bet would be to replace the inverter first then the backlight. Good Luck and let us know how it is going.
