@Kamal i have an Acer Aspire and had the backlight issue, tried the acpi_backlight change to the grub but didnt notice any improvement ie screen was still dark at startup. I then used the decrease backlight and this increased the brightness, so it seems that the settings are inverted as using the hardware keys to decrease the backlight actually increases the screen brightness.
@Kamal i have an Acer Aspire and had the backlight issue, tried the acpi_backlight change to the grub but didnt notice any improvement ie screen was still dark at startup. I then used the decrease backlight and this increased the brightness, so it seems that the settings are inverted as using the hardware keys to decrease the backlight actually increases the screen brightness.