Laptop powers on, no display or HDD activity

My laptop is a Gateway NV52. When the power button is pressed, the blue power light turns on, the fan and CD/DVD drive whir for a few seconds and stop, but the screen remains off (no backlight, no display visible even with a flashlight) and the hard drive activity light does nothing. It remains like this until I hold down the power button again and it shuts off.

The same thing happens whether the battery, AC adapter, or both are in use. The AC cord still appears to charge the battery. If the lid is closed, pressing the power button does nothing. Some of the touch-sensitive light-buttons at the top still illuminate when touched (volume, quick program launch, Gateway backup) but nothing else happens.

Yesterday I had the same problem but taking the battery out and running it on the cord fixed it. I shut it off, and now that approach nor any of these others have had an effect:

- Unplugging the cord and removing the battery, holding the power button for 60+ seconds
- Removing both RAM sticks and re-seating only one of them
- Removing the hard drive
- Plugging in an external monitor

Should I try unplugging the laptop's keyboard/mousepad/light-button-bar? Removing the CD/DVD drive?

I have had the computer for around 2 years. When it worked briefly yesterday after the battery-removal fix, nothing was out of the ordinary and I used it for several hours.