This could be caused by multiple factors:
Firstly, you can try to connect the laptop to a monitor to see if the graphics card is working. After you turn on your laptop, try pressing Fn + F4 to switch the display from the laptop to the monitor.
Secondly, try to open the screen to a wider or smaller angle than 90 before pressing the power button. This is a common possible issue for laptops.
Also, you can check out information on HP Forum 1 and HP Forum 2 for additional details.