When Hit Power Button Computer Would Not Boot?

I'm working on a gal's computer (HP 2000 laptop). Her problem? When she hit the power button, the computer would not boot. No BIOS screen, no boot screen, no HP screen. Nothing. Just a blank, black, backlit screen with no activity on the HDD indicator LED. If I remove the hard drive, however, then the computer will boot to the point of giving me a message instructing me to install a hard drive.

So you'd imagine the issue is with the hard drive. I hook her HDD into a free slot on my desktop to check the device. I'm able to access all files and it checks out okay. But if I put it into her computer, all you get upon touching the power button is a blank, black, backlit screen.

I'm assuming at this point that the boot partition on her HDD may be corrupted and a reformat and clean install are needed. I was able to back up her personal folders. However, there is no COA sticker on her computer (thus no Windows Key), just a "Windows 8" sticker. She said her computer did not come with a set of discs either (HP puts recovery data on a second HDD partition, which I am unable to access at this time). I asked her to contact HP and request a set of recovery discs for her computer, so that is where the process is at right now: waiting for a reply from HP.