yes the power cord i purchased has the "black box" inline and the voltages match 16v=4.5a and no hickor,y the laptop isnt under warranty

My brother originally had the laptop and had it up and running fine. he was in windows and whatnot. a few days later when i stopped by to pick it up the battery had died and it hasnt booted up since. Ive let the battery recharge since and i no longer get an orange battery light, it is green and not blinking. Ive also just noticed something as I was typing this post. with the power cord plugged in, I can turn on the laptop and the lcd screen will light up, i hear the fan whirring fast then slow, fast then slow, once again no post. i unplug the power cord and turn it on with just battery power the lcd screen will not light up, i just hear the fan whirring fast then slow fast then slow. could this be a MB problem? ive since removed the hddrive and put it back in checking to make sure it is in all the way. Ive also taken out the 2 128 mb ram chips and inserted them back in checking to make sure they are in correctly. Ive also tried just one chip ata a time and still nothing.. there must be SOMEONE who has had a similar problem? or am I up the creek?
"edit" and yes ive just let it sit but it still wont do anything. What concerns me is the "whirrrrring" of the fan it isnt static.. it whirs fast then slow and so on....
desparate for a solution...
War