it turns on but the screen is blank

Hi,

Is the HDD drive light (green light) on the front edge of the laptop turning on?

Can you hear the Windows welcome theme music, indicating that the laptop has booted into Windows successfully?

If not then perhaps the laptop has not fully turned on or has not booted into the OS.

Try the following just in case it is a corrupted BIOS that is causing the problem.

Disconnect the charger from the laptop. (if connected).

Shutdown the laptop if turned on.

When the laptop has completely turned off, remove the battery from the laptop.

Press and hold the laptop’s Power On key for 30 seconds and then release.

Replace the battery pack.

Reconnect and switch on the charger.

Try to start the laptop in the normal way and check what happens.

What OS is installed?

If so, then connect an external monitor to the vga port on the right side of the laptop and check if there is a display on it. You may have to press the appropriate function key on the top row of the laptop to switch between the laptop screen, the external monitor or both. (it may require that it is operated together with the Fn key but not sure for your model).

If you can see a display on the external monitor, try shining a torch at an angle close to the laptop screen and check if you can see an image at all. It will be very faint so try this in a darkened room if possible.

If you can see an image on the laptop screen then you have a backlight problem.

It could be a faulty display inverter or a faulty backlight cable or cable connection at either end, inverter or systemboard.(see p.49 of the service manual, link below).

If you can’t see an image on the laptop screen, then you may have a faulty LVDS cable or cable connection at either end, systemboard or display or a faulty display.

If you don’t have a display on the external monitor then you have a fault on the systemboard.

HP Compaq 6910p Notebook PC Maintenance and Service Guide