Laptop screen won't come on.

Amacey said:

Right so I have tried now to boot the laptop and get the screen working using two different motherboards, and also two different HDD.

There just seems like no power to the screen at all, for some odd reason.

I have a spare screen VGA cable, so tomorrow I will try with a new one of them. However I have tried using an external screen and all I get when I try that is a "No signal" message on the external screen.

Amacey
Try this trick. If the screen is black with no light emanating from it boot up the computer then take a flashlight and shine it at an approximate 45 degree angle on the screen. If you see anything Including a dos blink cursor in the upper left then you most likely have a blown inverter. Like florescent overhead lighting the floro tube in a laptop needs a burst of energy to get it going. so the inverter is like a ballast box. Inverters are inexpensive and fairly easy to find on ebay.

External screens on some laptops need the hotkey pressed in order to enable them. usually cold booting a laptop with an external plugged in will work but from my experience not always.

Right so I've looked using a torch and no there wasn't anything on the screen still. I have now tried using a new screen vga cable and also that didn't work. Seems like no power is going to the motherboard or parts. You hear a whirling noise when you turn it on but no fans or anything come on. The HDD light flashes and then doesn't come on.

Also tried booting without HDD and that doesn't work either.

The only thing I can think of that you have probably tried but haven't mentioned is booting with different ram. I have seen ram that has failed keep the bios from accessing any other hardware. Also you can look at the power adapter and or try a spare or universal to see if perhaps there is a low voltage issue. You have tried another motherboard so I doubt there is an issue of power to the mobo (since this is a laptop) unless it uses a DC Jack that is cabled and not a solder on. I would look at those too things. I really can't think of anything else.

When you used the other MOBO did you use the original ram and Processor?

You mention a whirring noise when you power on. Any way to pinpoint what is whirring? Perhaps a dvd in the drive? (pull the drive out and see if it stops). The only things I can think of that would make a noise like that are cd/dvd drive, hard drive (which you said you tried booting without), and fan(s). I would try to boot bare minimum which is:
1) no drives cd/dvd or hard drives
2) no memory or minimal and or different sticks if possible.
3) no keyboard (just unplug the ribbon cable)
4) no battery
5) different power adapter if possible

Amacey said:

The power adapter is cabled and not soldered, so I am going to try a different power adapter. I have purchased one so when I get it, I will let you know the outcome. Thanks everyone!

No problem Amacey, BTW what I meant by soldered is the DC Jack in the inside of the machine not the Power adapter. I have run into issues with some brands of laptops that route the DC Jack cable too close to a DVD drive that Vibrates. And hence a short or open whichever the case may be. A lot of internal DC Jacks are Soldered onto the Mobo itself which if yours is like that you eliminated the DC Jack issue by changing mobo's.

I see.. so as you might observe there is a possibility of an open there. if there is wear on the cabling I would replace it. Since you are replacing anyway it's probably a moot point. looking forward to knowing what you find out. Good luck.