The switch turns off the backlight when you close the LCD display to save the laptop battery power.
What could be wrong?
Its possible that the LCD lid close switch stuck in the closed position and the backlight stays off even when you open the LCD screen or turn on the laptop.
I would try reseating the video cable connector on the back of the LCD screen first and check if it fixes the problem.
Related articles: Fixing notebook LCD screen with water damage.The video on the LCD screen is garbled.You can try to fix the problem by reseating the video cable on the back of the LCD and on the system board.Here are some tips and tricks for troubleshooting and fixing laptop video problems.If after tapping on the LCD lid close switch the backlight stays on, you fixed the problem.Usually it is a small plastic pin located close to the LCD hinges.Laptop has bad video on the LCD screen.Heres a notebook display assembly diagram.

If the external video is fine, you have a problem with the LCD screen or the LCD video cable.
Check the LCD lid close switch.
Try to tap on the switch a few times to turn on the backlight.
Fixing laptop backlight problem.
In this case I would blame the FL inverter board.I understand that these tips will game of thrones hd 720p season 1 tpb not cover all video problems with portable computers.Most likely it is just a bad connection between the LCD display and the system board.It is also possible that after tapping on the LCD lid close switch the backlight works fine, you see a normal video on the screen for some time and then the backlight turns itself off again.Source: Hi there, Save hours of searching online or wasting money on unnecessary repairs by talking to a 6YA Expert who can help you resolve this issue over the phone in a minute or two.If you see the same garbled video output on the external monitor most likely it is not the LCD screen problem.

Look at the LCD screen very closely and check if you can see a faint image on the screen.
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If you have a different problem, you are welcome to leave a comment and I will try to help you if I can.