Display dark but device is turned on

MacBook Pro display screen is black, however it is turned on because I can see the brightness/sound control graphics on the mini display bar on the keyboard, they can be pressed but don’t do anything or make screen brighter.

Have tried restarting device multiple times and different combinations of keys and power off button. After holding the power button, the display bar graphics disappear and the MacBook makes the restart sound, but doesn’t show a loading Apple. Then after a minute the display bar controls reappear, while the actual screen stays dark.

Left the computer for a few minutes, the keyboard display bar graphics/controls disappear but reappear when I touch the launchpad. But screen still dark.

How to fix this?