Refuses to turn on

I hope someone can help me on this one. I recently acquired a dell latitude d600 laptop and I really like it. It has been working flawlessly for the last few weeks. I have not downloaded or installed anything new recently. All of a sudden, it stopped turning on! No lights, no fan, nothing. I have a friend who has a d600 and I swapped my battery and ac adapter to his and it worked perfectly. I put his in mine and nothing. I tried another web site and it was suggested that I press hard on the docking port on the back while I pressed on the on button,etc. Nothing works. I removed and reinstalled the hard drive, video card, and ram and changed ram slots to no avail. Can anyone out there shed some light on what is wrong and how to fix? It was suggested on another forum that I replace the reserve cmos battery but I thought that it was only for time and bios settings? Please help.

 

Press the FN plus power button. This should bring it into diagnostic boot mode.

 

Thank you atbnet, I will try that on monday when I have access to the computer again and report back to you.