System hangs during boot

[bfb]

I am having a problem with a fresh install:
On a Dell Inspiron Mini 1012, the boot process hangs during some systemd stuff
On SECOND run : I.e it works fine on first run after install but hangs  after re-booting. This is my first try with the series 3 on this machine which was running 2.8 perfectly.

System hangs during boot after printing three or all of these lines;

[  OK  ] Created slice system-systemd\x2drfkill.slice.
        Starting Load/Save RF Kill Switch Status of rfkill0...
        Starting Load/Save RF Kill Switch Status of rfkill1...
        Starting Load/Save Screen Backlight Brightness of leds:dell::kbd_backlight...
I THINK

This bug is caused by the file /var/lib/systemd/backlight/platform-dell-laptop:leds:dell::kbd_backlight created by (I guess) [email protected]

As that file is re-created at shutdown, I have to mask the service systemd-backlight@leds\:dell\:\:kbd_backlight.service with:

sudo systemctl mask systemd-backlight@leds\:dell\:\:kbd_backlight.service

so kernel-4.4.0-93 doesn't hang at boot.



BUT I can’t get into the system to do this.
I tried going in in recovery mode, but it demands a root password for maintenance.

Can anyone help?