Can you provide more details about the issue that you have? Can you hear the fan or the hard drive spinning up? If you can that the problem might be found within the video chip /the North Bridge/ which have gotten desoldered. Sometimes where there's not enough cooling the video chip "looses" its thermic paste and does not give signal to the display.
If you can't hear any noise coming out of your laptop probably it's because there's a PSU or motherboard failure.
I suggest, if you can, pull out the drive and try to connect it to another PC via SATA-USB cable as an external drive.