It is possible the laptop appears to be dead because the AC adapter is bad (and the battery is discharged).
If you know that the AC adapter is working properly and it outputs correct voltage but the laptop is still dead, most likely you have a power issue on the motherboard (or power board on some laptops) and it has to be replaced.
If your laptop does not start at all or it starts but will not boot properly, it’s possible that you can fix the laptop at home without taking it to a repair center. I’m not sure if I can cover all situation at once, so I will update this post as more examples come into my mind. First of all in this situation check the AC adapter. If you cannot do that, find a known good AC adapter and use it for testing the laptop.
You plug the AC adapter but the LEDs (power light, hard drive light, battery charge light, etc…) do not light up and the laptop will not react at all if you press on the power button.
After that plug the AC adapter ans try starting the laptop again. Try installing the memory module into the other slot (if it’s available).
If you have two memory modules installed, try removing them one by one and start the laptop just with one memory module installed.
Go to my previous post witch covers laptop video problems in more details. Most likely you hear this noise because of a faulty hard drive. Situation 6 It could indicate a problem with the laptop LCD screen, video cable, graphics card or motherboard.
You can remove the hard drive and start the laptop without it. Here’s my previous post witch covers troubleshooting bad images on the screen in more details.
When you plug the AC adapter the power LED and the battery charge LED light up.
If the laptop starts fine with one memory module in both slots, but will not start with the second memory module in both slots, the second memory module is faulty. If the laptop starts fine with both memory modules when they are installed in the slot A, but will not start with both memory modules installed in the slot B, the slot B is faulty and you’ll have to replace the motherboard or use only one memory slot. In this situation test the memory module as I described in the situation2. Most likely you are getting a beep error because of a faulty memory. In this situation test the laptop with an external monitor. Also this problem might appear because of a faulty memory module, try some tips from the situation 2.
If the external screen works fine but there is no video on the laptop LCD, most likely there is a problem inside the laptop display assembly. The laptop still boots ans you still can see the screen, so you can run the memory test. Run the memory test and if it fails, replace the faulty module.
If after tapping on the LCD lid close switch the backlight stays on, you fixed the problem.
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. Try to reseat cables on both end of the FL inverter to make a better contact between the cables and the FL inverter board.