Turn off notebook display

As I’m running HA on a old notebook, I’d like to switch off the display. I do not needed. Best thing would be to even close the lid. I tried to do it via ssh but wasn’t able to do it.
Any ideas?

I am using the Generic x86-64 version

I tried # echo 5 > /sys/class/backlight/acpi_video0/brightness
but got bash: brightness: Read-only file system