LCD Screen goes black and goes back to normal

[aibi]

I've asked this question a long time ago regarding my mpx player but the answer was quite open. Now I really want to figure how to fix it since the player can charge up again (I thought it was really dead).

Depending how I hold it and what angle I tilt it, it lights up and then doesn't again. I know it's a problem probably with the wire inside the player, I've opened the cover/back and looked inside but not sure what is actually going on in there.

I'm hoping someone has an idea what to do to fix the backlight. It's really inconvient when trying to watch a video...

Thanks.