These steps may help, I’ve used them before to fix issues with no display image. ——- 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. (1) Connect an external monitor to the notebook. (2) If the computer screen does not display on the external monitor, press F4 (or the key with this symbol ) until the screen image displays. (3) 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. (4) If the screen is still black after updating the chipset...
I think the DFU restore suggestion fixed mine. I only did the DFU restore because of a different issue but apparently it fixed my Auto-Brightness at the same time. Thanks!!!
