I have the HP pavilioin dv2000 too. I encountered the same problem. I did everything i though possible (reseated the battery, reseated the ram) and everytime i hit the power button, i would get all the blue lights on but no screen. And it is non responsive. Fed up i held the power key down for no less than 2 minutes and ta-da the computer responds by turning off. After i pressed the power button again, it started normally.
Hope it helps. Take care.
Sure, you can try to boot up in safe mode. Don't know if that will work in this situation, but that might tell us something.
We most probably have one of three things happening. Either it's an LCD display problem, a bad motherboard or something is hanging things up.
For the LCD problem, start it up in a dark room and see of there is a faint display visible.
We'll not worry about the motherboard for the time being.
As far a determining if there is a system hang, we need to take it down to bare bones. This is the procedure that I wrote up: Could be a power problem or could be a motherboard problem. However, before we jump to any conclusions, there are a few things that we can try.
First, simply remove the battery and try to power up. Defective batteries can cause this type of symptom.
If that doesn't work- Reseat everything, or take it down to "bare bones" and see what happens.(Remove the battery and don't replace it until you are done with these processes)
Reseating everything means to tear it down to the point that you can access every connector and removable component. Disconnect each cable, and component, one at a time and plug it back in. While you're doing this, check for water stains (mineral deposits) and gently clean them with alcohol if any are found. If it doesn't come up after doing this, try the bare bones approach.
By bare bones, I mean to disassemble to the point that you only have the a/c adapter, motherboard, 1 stick of memory and the display hooked up. At this point, if it doesn't come up farther than it does at present, you more than likely have a bad motherboard.
If it does show signs of life, start reconnecting one item at a time, and try to power up after replacing each item or connector. If you replace/reconnect something and it no longer does anything, you have just located the part that is bringing your system down.
Using this approach, I have seen memory cards, hard disk drives, keyboards, mice, touchpads, floppies, cd readers all cause this type of problem. One note on this procedure is that when using the word "disassemble", that doesn't necessarily mean to actually take it out of the computer. It is referring more to making sure that each item is totally disconnected.
Go ahead and try these things and let me know what happened (or didn't happen, as the case may be).