After my Jan 11 update (first updates since early Dec) the screen shows all the boot messages (AFAIK), but when it appears done booting the screen fades, becomes unreadable and is shaking. I lon the past,oked at dmesg and journalctl but didn't see any error messages.
I have been turning the screen off using "echo 1 > /sys/class/backlight/rpi_backlight/bl_power".
However, as of Jan 11 "ls /sys/class/backlight/" shows no files/folders including no folder named "rpi_backlight".
How to troubleshoot or fix or what to rollback?