My HP Laptop screen is black

[Scar_MoonYT]

So, I have an HP EliteBook 840 g3 and the screen is black but the fan is running and the LED light in the keyboard turn on at first but then they turn off. I have tried holding down the B button, the Windows button and the power button for a second. I can't take out the battery because there is no place to take out the battery. Please Help, I really want to get back to animating and playing video games. 

[Lil_Boy_Blue]

Hi
First:- Turn off the computer, press and hold the PWR button for 4 seconds.

Then - Leave only keyboard and mouse connected, disconnect all externally connected
devices such as Docking Station, USB storage devices, displays, and printers.
Unplug the AC adapter from the computer.

Next - Press and Hold the Power button for 15 seconds to Hard Reset.
Rinse and Repeat; Re-Connect the AC adapter.

NOW begin checking/testing/proving the Hardware is fit for purpose.
Power on your PC, press ESC (repeatedly), then F2 at the prompt.
Choose System Tests (Fast Test does a 4 minute hardware check).