No screen on Acer Aspire 5920G laptop

Hello,

I have a problem with my Acer Aspire 5920G laptop.
Recently, the laptop crashed during a program, where sound and image stuck (blurred image with colors). The only way to put my laptop off was to press and hold the power button for 5 seconds.

If I wanted to boot again,the light in the power button go and keeps on, i hear fans running and the control lights blink in the beginning sometimes.
But the screen stays black and dark. Nothing to see, no backlight, no flashes, no-acer startup screen, no blinking cursor ...
When I press the power button now one time, the laptop is immediately turned off (so i think Windows does not start up).

If I try to boot with an Ubuntu live CD, i hear the CD-ROM drive turning, and the laptop seems to end up somewhere in a menu, but the screen does nothing.
When I press the power button now one time, the laptop keeps running. To turn off i have to press and hold the power button for 5 seconds.

I tried to boot with an external screen (once with a VGA connection, once with an HDMI connection), but this makes no difference.

I have disconnected power and battery and pressed and holded the power button for 45 seconds (to reset bios). It does not matter.

I have changed the RAM from position (the other slot). It makes no difference.

The screen shows nothing (at any time), not even a backlight.

Does anyone know a possible cause of this?
- Is the screen broken?
- Is the graphics card broken?
- Is this another known issue?


What can I do to detect and solve (eventually) this problem, without sending it directly to the Acer repair service.
Maybe some simple checks of a checklist in order to exclude somethings.