HP ZBook 15 G6, Zorin OS 18.1 Pro, BIOS R92 01.32.00, Nvidia T2000. Since a recent update: random shutdowns, brightness stuck (slider/Fn keys do nothing), and internal display stays black after suspend (HDMI still works).
Tried: acpi_backlight=native, acpi_osi=Linux, i915.enable_dpcd_backlight=3, switched prime-select to on-demand, added resume xrandr script with retries. Confirmed kernel-level: writing directly to /sys/class/backlight/intel_backlight/brightness (0-1023) has zero visible effect on the panel, even without sleeping.
System logs show ACPI BIOS errors (AE_AML_PACKAGE_LIMIT) aborting _TZ.GETP thermal methods. Suspect broken ACPI firmware table. Anyone seen this on ZBook G6 specifically, or found a fix beyond a BIOS flash?
Did You received a Kernel Update to Version 7.0? If yes, try to go back to the older Kernel. To do that, choose on the GRUB Menu ''Advanced Options'' and there choose the 6.17 Kernel.
The get the GRUB if not available, press on Startup Esc. If that shouldn't work try the left Shift Key.
If both shouldn't work, You can enable the GRUB Menu manually. When in Zorin, open a Terminal and type:
The 20 makes that the GRUB Menu appears 20 Seconds. Should that be too much or less for You, You can use a different Value like 10, 30 or 50 for Example. Or You can use -1 for showing the GRUB Menu as long as You give it an Input.
When make the Changes, press ctrl+o to save, Enter to confirm and ctrl+x to exit. Back in the normal Terminal Overview type sudo update-grub to make the Changes affect. Don't forget that! Without it, it will not work.
I read that this parameter helped also for other Dells and HP spectre which had problems with the brightness after the upgrade to kernel 7.0.0-28. Also the kernel version 7.0.0.-14 seems not to cause this problem.
