When you push on the power button, the power light on the laptop turns on but the screen shows no image. The laptop screen remains black and blank. Video on the external monitor also not working even though it used to work fine before.

Possible cause:

1. Memory failure.
2. Video card failure.
3. Motherboard failure.

Possible troubleshooting steps and repair solution:

1. Try reconnecting memory modules, maybe one of them is not making good contact with the memory slot.
Try removing memory modules one by one. Maybe one of the memory modules is bad. The laptop might start properly when the faulty memory module is removed.

If you have only one memory module, try moving it to another slot. Maybe the slot itself is bad.

Try replacing memory module with another known good module.

2. If you have a discrete video card, which is not common, there could be a problem with the video card.

First, try reconnecting the video card to the motherboard. Maybe connection between the video card and motherboard is bad.
If reconnecting the video card doesn’t help, try replacing it.

3. In most newer laptops the video card integrated into the motherboard. If the video card fails, you’ll have to replace the motherboard.

If playing with memory modules (as explained in step 1) didn’t help, most likely there is a problem with the motherboard and it has to be replaced.

Spontaneously the laptop screen will “freeze” the current image and then slowly turn white with some faint gray blotches. If I move the top of the laptop toward me, sometimes the image comes back to normal. If I move it backward, then the image freezes and goes white again. The laptop works fine with the external monitor.

Possible cause:

1. Bad connection between video cable and LCD screen.
2. LCD screen failure.

Possible troubleshooting steps and repair solution:

First of all, try reconnecting the video cable on the back of the LCD screen. It’s possible that video cable is not making good contact with the LCD screen.

If reconnecting the cable doesn’t help, most likely this is LCD screen failure. Apparently there is a faulty component or solder joint on the screen controller board. In this case the LCD screen has to be replaced with a new one.

One half of the laptop screen is completely black. The second half of the screen works properly.

Possible cause:

LCD screen failure.

Possible troubleshooting steps and repair solution:

If one half of the laptop screen stopped working but the second half still works properly, this is LCD screen failure.

The LCD screen cannot be fixed at home. You’ll have to remove the failed screen and replace it with a new one.

The laptop screen goes darker when the power adapter is plugged in. When the adapter is unplugged, the screen becomes brighter.

Possible cause:

Wrong setting in the power management software or BIOS.

Possible troubleshooting steps and repair solution:

Most likely the problem is related to the settings in the power management software or BIOS.

Find the power management utility installed on your laptop and check the LCD screen brightness settings. Apparently, the LCD screen brightness settings are higher for the battery mode. Increase LCD screen brightness settings for the AC mode and the problem will be fixed.

In some laptops you can change LCD screen brightness in the BIOS menu. Enter the BIOS menu and make sure the LCD brightness is set to maximum for the AC mode.

The lower part of laptop screen displays garbled colors and the upper part of the screen works just fine.

Possible cause:

LCD screen failure.

Possible troubleshooting steps and repair solution:

When a part of the laptop screen works properly and another part has garbled image and colors, the problem is related to the LCD screen failure. The screen cannot be repaired and has to be replaced with a new one.

The laptop screen shows vertical dotted lines. The dots are red and moving up and down. The external monitor connected to the laptop either has garbled image or shows same dotted lines.

Possible cause:

1. Failed memory.
2. Failed video card.

Possible troubleshooting steps and repair solution:

If the problem appears on both the laptop screen and external monitor, it’s not related to the laptop LCD screen or video cable. Most likely the problem is related to the faulty memory module or video card.

Download Memtest86+ (google it) and test laptop memory. If the laptop has two memory modules installed, remove them one by one and test separately. If one of the memory modules fails test, move it to another slot and test again, just to confirm that it’s bad module, not the memory slot. Replace the failed memory module with a new one if needed.

If laptop memory passes test a few times, most likely there is a problem with the video card. In most laptops the video card is a part of the motherboard and cannot be removed and replaced separately. If the video card fails, you’ll have to replace the entire motherboard.

The laptop has a few very thin colorful lines on the screen running from top to bottom. These lines are vertical and spread with irregular intervals. Lines appear on the screen even on the BIOS level.

Possible cause:

LCD screen failure.

Possible troubleshooting steps and repair solution:

This is LCD screen related failure. Most likely there is a problem with the LCD controler board on the screen.

In this case you’ll have to replace the LCD screen or use the laptop as is. The screen cannot be repaired, it has to be replaced.

The laptop screen flickers on and off.

Possible cause:

1. Screen inverter failure.
2. Backlight lamp failure.
3. Bad video cable.
4. Video card failure.

Possible troubleshooting steps and repair solution:

First of all, take a closer look at the screen when it flickers. Is it losing just the backlight and the image stays on the screen or it loses both the backlight and image?

1. Laptop loses backlight and image when screen flickers.
- test your laptop with video on an external monitor. If video flickers on both the laptop screen and external monitor, there is a problem with the video card.
- if you see flickering only on the laptop screen, it’s either bad video cable or faulty LCD screen. Try reconnecting the video cable. Try replacing the video cable. Try replacing the LCD screen.

2. Laptop loses only backlight when screen flickers. The image is always on the screen.
- bad screen inverter board. Replace the inverter board.
- bad backlight lamp inside the LCD screen. Replace the LCD screen.

There are horizontal flashing lines running across the laptop screen. The laptop starts fine and you still can see the picture, but there are flashing lines running across a part of the image.

Possible cause:

1. Video card failure.
2. Bad connection between video cable and LCD screen.
3. Bad LCD screen.
4. Faulty video cable.

Possible troubleshooting steps and repair solution:

1. First of all, test the laptop video output on the external monitor. If you see same flashing lines running through the image on the external monitor, you have a problem with the video card. If flashing lines appear only on the laptop screen, the failure is not related to the video card.

2. Just in case, try re-seating the video cable connectors on the motherboard/video card and maybe the back of the LCD screen. It’ s not likely but possible that connection is loose and reconnecting the cable will fix the flashing lines.

3. If re-seating the cable connectors doesn’t help, most likely you have a faulty LCD screen. The LCD screen has to be replaced.

4. If replacing the screen doesn’t help, try replacing the video cable. It’s very unlikely that this problem is related to the video cable but there is a slight possibility of that.

The laptop backlight stopped working without any reason. The screen was working fine a while ago but now it’s very dark. The image is still on the screen but it’s barely visible. When the laptop rebooted, the screen remains very dark.

Possible cause:

1. Backlight inverter failure.
2. Backlight lamp failure.

Possible troubleshooting steps and repair solution:

1. Most likely this is related to the backlight inverter failure. The inverter board is installed inside the laptop display panel and in most models mounted below the LCD screen. When the inverter board fails, the laptop screen goes completely dark and the data on the screen becomes barely visible. There is a good chance to fix the backlight problem by replacing the inverter board.

2. If a new inverter doesn’t fix the problem, apparently you have a faulty backlight lamp inside the LCD screen. Replace the LCD screen.

It is possible to replace just the backlight lamp but it’s not easy and should be done by an experienced technician.