dim laptop screen

Got Sony Vaio PCG-71315L
The screen got broken, and we had to replace it , we bought

and once we replaced the screen, i can barely see what's going on in the background, cause there is no light.
Note: there is no inverter for this screen.

i tested my HP screen, it is the same size and same connection, and it gave the same result, so the two screens (i doubt they are both bad.
could it be the cable that connects the screen to the mother board ?
or is there anything else might be missing ?
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Press the Fn key and the F9 F10 or F11
there will be a sign on the key
connect the AC adapter and try these things
sometimes due to power saving mode the laptops running on batteries dim the display
if both of these things does not work then, its the display issue
Da_Ch0senAuthor Commented:
I did try all of that.
Even in the bios and at the POST there is no light enough to read.
I know it's a display issue. But as mentioned  earlier I did change the screen and still same problem. Could it be anything else ? (Like the cable that connects the screen to the motherboard for example.
Could be because the screen isn't correctly recognized by the motherboard BIOS or power control settings (like the ones for sleep or power savings mode) and since it doesn't its still using the settings its at before the swap.
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Da_Ch0senAuthor Commented:
No even the old screen the cracked one. It's showing dimmed as well.
It used to be cracked but bright lit. Not anymore !! What could be need changing ?
is the display ok on an external monitor?
if not, your video card has problems
if that is ok - it can be your LED screen does not get the 12 V for LED backlighting; could be a cable or connector problem

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Da chusen  what was the solution?
also - why the B grade?  if i gave the correct answer, you should give an A
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