These steps may help, I’ve used them before to fix issues with no display image.[br]
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The screen might remain black when there is a corrupted graphics driver or a problem with the LCD display back light. To test the display, attach an external monitor and restart the computer. This test is helpful if the display is black but you can hear that the computer is operating.
# Connect an external monitor to the notebook.
# If the computer screen does not display on the external monitor, press F4 (or the key with this symbol ) until the screen image displays.
# If an image displays on the external monitor, there might be a graphics driver conflict with the notebook LCD display. With the external monitor connected, go to ++HP Customer Support - Software and Driver Downloads++. Download and install the latest graphics and chipset drivers for your specific computer. If an updated BIOS version is available, see ++Updating the BIOS++ for steps to install it.
# If the screen is still black after updating the chipset and graphics drivers and BIOS, the LCD might be defective. Contact HP for technical assistance or send the notebook for service.
# If you can hear sounds of operation but no image is visible on either display, go to the next step.