I've changed the inverter board and the cable but..

My problem is:

The computer is on but the screen is dark.

So

1.I tried the brightness (F1&F2 key) but the light goes dark again.

2.I also have tried the resetting.

3. Changed the inverter board

4. Connected to the TV, it works fine.

5.While the screen is on (sometimes, the computer stays on in brightness 2~3), I disconnected the black cable on the left side of the inverter board, the computer lights on for a sec.

6.finally I've changed the display data cable today but it's still not working.

I'm thinking about returning the board and the cable and order a new lcd.

But I'm not sure it's the lcd problem..:(

Please give me some advice!!