Ok. The only way to arrive at a conclusion is by testing the involved components 1X1 via process of elimination. There is no single program that tests the complete motherboard.
An important clue is here:
No beeps. The fans continue to run.
I assume that the monitor is dark and unresponsive. I assume from your quote that there used to be a system beep when booting (correct me if I am wrong), and now there is none. However, the fans spin up and I assume that the power-on light on the motherboard ("mobo") is on (if your board has one-some don't). At this point, the boot signal from the power supply is not even reaching the BIOS; the "beep" that you usually hear indicates keyboard recognition and that comes from the BIOS long before the hard drive is recognized. Computers will not boot unless a keyboard is plugged in. That indicates a low-level hardware failure. A low-level failure can be caused by only one of four things: a failed CPU, a failed Motherboard, a corrupted or failed BIOS (extremely rare), or a failed Power Supply.
>First, establish if your computer is still under warranty or not. HP may have told you that already.
>Next, reset the BIOS. I know you removed the battery already, but I have to cover all the bases. In your users' manual you will find a jumper switch on the motherboard that you move from one side to the other, and that clears the CMOS entirely. Power down; unplug your computer from the wall socket; remove that battery; move the Clear CMOS jumper per your book instructions, usually from one set of pins to another, wait 10 seconds, then move back into original position. Replace the battery and try to boot. Now...if your board does not have a clear jumper, then skip that step. Just remove the battery with the power cord disconnected.
>While the case side is open, check the motherboard capacitors for failure. This is becoming a common problem as companies are buying cheaper capacitors and they fail regularly. Capacitors look like small, "Quaker Oats" round boxes set on-end. They are commonly silver color, but can be black, green or brown. The tops of these should be perfectly flat on top; if there are any that are bulging upward, and if there is "goo" on the tops, possibly running down the side, or even on the bottom, that capacitor has failed. Even if the cap to is bulging with no electrolyte seeping out it is bad.
There are many capacitors on a motherboard, some large and some small. Check them all. The easiest way to do this is disconnect the computer and lay it on its side with a bright light shining in, a flashlight is good. If you find any, you have found your problem.
Additional info link: http://badcaps.net/pages.php?vid=5
Note the pictures on the right hand side. If you find even only one on your mobo, you have found your problem. I have also attached a picture I took of one unit I recently worked on. Note the good caps on the left, and the bad caps covered with electrolyte on the right.
>As Donetao already suggested above, run a check on your hard drive. I do not think this is the problem, but we must be thorough. A failed hard drive will not prevent the POST screen from appearing (POST=Power On Self Test). Download Seatools For DOS (free) from my link; in the site screen, click "DOWNLOADS" tab, then "Seatools For DOS" and save the file. Burn the ISO file to a CD. Reboot with it in your drive. Hopefully your BIOS is set to CD=First Boot Device, since you cannot access your BIOS to change it. If it is not, this may not work. In the screen that appears, first check that SMART has (or has not) been tripped. Then click the upper left corner of the screen for the short test and let it run. It will notify you either Pass or Fail. This is from Seagate Corp. but will test all other drives, not just Seagate. **I suspect that the DVD drive will not be recognized, so let me know what you find.
>The only way to check if a CPU has failed is to remove it and install it on a different computer that you know is running properly. Realistically, that will be difficult for you to do. As a reality check, it is extremely rare that a CPU fails. I have had only one fail on me in all the years I have been doing this.
>The only way to check a power supply is either to purchase a tester, they run between $20-$50 on average, or change out the power supply with another you know is good. Realistically, it appears that your power supply is enabling the fans to spin up. If you have a power-on light on the mobo itself and it is lit, that is another indication that the board is getting power. Here is a link to Newegg, the Rosewill tester on the top should do it. I am not suggesting that you do this, just giving you options.
>A virus will not prevent the POST screen from booting, although one could prevent Windows from loading. But that is not your problem. You are not getting keyboard recognition from the getgo. Without that you can't go anywhere.
Please check out the above, and get back to me. I would be very interested to see your results. Post back with any questions. Wish you good hunting!