Hello @meter_filler 
Does the adjustment of the backlight of your screen work? If so then the service can be masked, because it just tries to start a non-existing device.
Try this to check (not sure if this is the correct name):
systemctl status systemd-backlight@backlight:acpi_video0.service
Seems to be the same issue like here: [FAILED] failed to start pkgfile database update