I've downgraded to firmware 1.73 through the Gnome Firmware application.
The issue is not present on this version and I can reboot like a normal person.
I suppose I can figure out if it's 1.74 or 1.75 that breaks it.
Not really sure where to report this, I don't think it's Ubuntu
specific, I use
I came across this bug looking for a solution.
I can reproduce on 1.75 and now 1.76, W variant of the BIOS on my X390
Yoga i5 no vpro.
When you shutdown/reboot the laptop, everything shuts down like normal,
but my FnLock and Mute keys stay lit and the screen is black no
backlight. The computer
