Fault could either be faulty memory or faulty motherboard. Symptoms seem to be no post. I would double check that its no backlight. This is when the screen doesnt light up but you can make out that the screen is displaying something. Its easier to move the screen as back as you can and see if you can make out something on the screen. If there is something on the screen, then you need a part called an invertor. Otherwise, next step would be replacing or trying some test memory (RAM). After that, if still nothing on screen, take out the hard drive and see if it comes on. If it still doesnt, then its likely that the motherboard has gone faulty and you should seek a replacement motherboard. Easy to fit if you know how to deal with electronic devices, not so easy if you are not comfortable with being responsible for around 20-30 screws and remembering where they go!
Hope this information helps...
Kash
April 2008