Recently I reinstalled kali on my X270 - and sometimes the backlight was flickering.
A short search showed me that this issue is known, for windows you would have to do some yadayada with removing drivers whilst in savemode and that.
As I'm not using Windows - at least the information about the driver was helpful: it's the intel i915 stuff. Continued to search, I found a possible solution, tried it: success.
So: If you're experiencing something similar, first thing to do:
- open a shell as root
- check cat
/sys/kernel/debug/dri/0/i915_edp_psr_statusforPSR mode: enabled - change
/etc/default/grub' :GRUB_CMDLINE_LINUX_DEFAULT="[..] i915.enable_psr=0 [..]" - reinstall / reconfigure grub
- reboot (logoff isn't enough, as the kernel cmd line params are only read on boot)