If the power totally fails (i.e. power is cut off, LEDs turn off, fans stop, ... etc), then this more likely to be because of a short circuit developing in a failing semiconductor component, or a power supply problem.
However, if the laptop is still running & only the display on its LCD is cut off but the laptop itself stays powered on, then your laptop might be experiencing a failing screen inverter board, a failing screen backlight lamp, or a failing LCD screen cable.
TYPICAL INVERTER FAILURE SYMPTOMS
1. When you turn on the laptop, the screen lights up for a short period of time and then goes dark. You still can see an image but it is very dark, almost invisible and definitely not usable. When you restart the laptop, the screen lights up and then goes dark again. The laptop works fine with an external monitor.
2. Your laptop turns on but the screen remains dark all the time. You still can see a very dim image outline. The laptop works fine with an external monitor.
3. The laptop screen works fine for hours or even days, but sometimes it goes very dark as it mentioned above. When you restart the laptop, the screen works fine again.
Inverter failure symptoms are very similar to backlight lamp failure symptoms and in most cases you cannot tell which one is causing the problem until you replace either the inverter board or the backlight lamp. From my personal experience, inverter boards fail more often than backlight lamps. If you have to guess, replace the inverter first.
BACKLIGHT LAMP FAILURE SYMPTOMS
1. The laptop screen lights up only for a short period of time or will not light up at all. The image on the screen is so dim that you can barely see it. At the same time, an external monitor attached to the laptop works fine.
2. When you turn on the laptop, the screen works fine for a while, then start flickering and the light turns off. Again, there is a very faint image on the laptop screen and external video output works fine.
3. The screen works but the image has a reddish/pink tone. External video output works fine.
The backlight lamp failure symptoms are very similar to the inverter board failure symptoms. If you have to guess which one is causing the problem, try replacing the inverter board first.
LCD CABLE RELATED PROBLEMS
1. The image on the screen appears normal until you move the display up or down. When you move the display, the images on the entire screen starts to flicker, disappear or change collors. As soon as you stop moving the display, the image gets back to normal.
2. The LCD screen lights up but there is no image at all. The entire screen is blank. An external monitor connected to the laptop VGA port works fine, there is no problems with the external video output at all.
3. Image on the entire LCD screen is garbled. An external monitor works fine.
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