Aspire 6920 screen problems

Hi I was just wondering if anyone could help. I broke the screen on my aspire 6920 and tried to get it replaced. The screen was cracked but still lit up so sent it to a company who couldn't fix it and gave it back. I bought a screen for 100 and had it fitted but
It never hi lighted up. You can see the things on the screen if you put a torch to it
But it's not lighting up. The
Company who I gave it to the second time said it may be the inverter so I got one of them off eBay but that didn't solve the problem. The laptop seems to be working fine other than that but I can only get it
Working by plugging a monitor in, when you press some buttons sometimes it flickers on but never stays but when it doesn't flicker it looks ok.inwould love to fix it coz I'm lost without it
So has anybody got any ideas as to what the problem is please .

Thanks for your time. Adcol4