I've installed Ubuntu 12.04 on a Lenovo G500s Laptop. The screen is scrambled/shows weird artefacts during boot but that doesn't really bother me. What does is this:
The screen's brightness is always 0% on boot, which means that it is pitch black.
I've already searched this site and found two suggestions:
echo 50 > /sys/class/backlight/acpi_video0/brightnessin
/usr/bin/xbacklight -set 50in
Both work fine (affect the screen's brightness) when I execute them from the Terminal, but when I put either of them in
/etc/rc.local the display will still be pitch black on the login screen after a reboot.