Well,
You are on the right track. I would ask... What power supply did you switch it with (WATTAGE). Try unplugging everything except the Hard drive and MOBO and see if it boots up then. If so, then you need a more powerfull power supply (There's just not enough power kiptin, I'm givin' her all she's got!). If it does not, well, I am sorry then, because next step is most likely the motherboard. Make sure there are no jumpers on the motherboard set incorrectly (as in Clear CMOS instead of Normal) and that your cables are plugged in OK (try unplugging all of them except poer to MOBO and see if you can boot. If so, go one by one plugging them in).
If you try removing everything, even ram, and still no power, you have either a bad power supply or a bad motherboard!
Sorry! I just saw the first line about having the NEC Ready. Thats a laptop isn't it! The above still may apply, but not as easy if it is a latop. You could also have a bad switch or something, but it's not like you could short the power pins on the motherboard. I like laptop's alot, but... When something breaks, it usually stays that way!