Hi, I need help here. I have been searching on google and reading several articles trying to figure what's going on. Here is my situation.

I have a Sony laptop, model number is PCG-7142L. This is a Windows Vista Home Premium OEMAct system. Service tag is C6U0K0HG. Everytime I turned on the power, I can see the power LED light turned on (I can hear the system was running) and within 5 second, the light turned off (with a very tiny sound and then no any sound at all) and then in a second, the power LCD light turn on again. However, nothing showing on my screen. I mean nothing. not even showing the mouse arrow.

I have tried to hold F12 or F8 or "shift" Key and almost all keys on the keyboard but just nothing happening at all. I also tried to hook up another desktop monitor because I suspect the problem was my Sony Laptop screen was dead but still showing noting on that desktop monitor. I also tried to take off the battery and unplug the power for days and re-start my laptop, but nothing.

Here is probably my last hope before I throw my laptop to the wall. Can someone help me here.

Hi and welcome to the forums.

Do you have your laptop plugged into the charger when you try to start it up?

Yes, sure I did that and I done the discharge electricity thing too.

Good to see that you take care of your battery with the discharges.

This time at start-up, do not "hold" the F12 or F8 button, tap them repeatedly (several times) untill your BIOS screen will come up.

Do you have another computer or laptop, along with a USB by any chance?

I also did the tap thing too (F12, f8, and others). I didn't know which button I hit but there was one time, the screen did show and everything was normal so I took the chance to re-updated the bios but when I re-strat the laptop, it went back to same, black screen and the trick that I used didn't work no more.
Yes, I do have a desktop and another laptop available, all with USB ports. what I need to do next?
thanks for replying.

Originally Posted by changkuotai

I also did the tap thing too (F12, f8, and others). I didn't know which button I hit but there was one time, the screen did show and everything was normal so I took the chance to re-updated the bios but when I re-strat the laptop, it went back to same, black screen and the trick that I used didn't work no more.
Yes, I do have a desktop and another laptop available, all with USB ports. what I need to do next?
thanks for replying.

I think the button for your laptop is F2, try to tap that on the startup.

You need to access the BIOS (find the right button) before I can help you further.

Try these buttons:

[ESC] [F2] [F8] [F10] [F12]

Hi Windows8, after reading your post, I tried to re-start and continue tapping ESC, F2, F8,F10, and F12 one by one but still not working. pretty upset. do you think the motherboard is dead?

Originally Posted by changkuotai

Hi Windows8, after reading your post, I tried to re-start and continue tapping ESC, F2, F8,F10, and F12 one by one but still not working. pretty upset. do you think the motherboard is dead?

I don't think that the motherboard is the problem, I just think that your laptop has an unusual button that is used to get into the BIOS.

Try to restart, this time press [DEL]

still not working. I also tried "Shift" this time as well.

Originally Posted by changkuotai

still not working. I also tried "Shift" this time as well.

Hm. I'm not sure what to say right now.

The computer won't start, just a black screen with the power light on?

Does it show the make of the computer at start up?

for example: