Backlight not adjustable after panel repair

After exchanging the broken lcd panel for a new aftermarket one on my asus zenbook, the backlight is no more adjustable. Fn-Keys are working, the widget indicates that brightness ist adjusted but backlight seems to stick on 100%.

does anyone know how to fix this?

ls -l /sys/class/backlight/
insgesamt 0
lrwxrwxrwx 1 root root 0 23. Apr 08:28 amdgpu_bl0 -> ../../devices/pci0000:00/0000:00:08.1/0000:04:00.0/backlight/amdgpu_bl0
lrwxrwxrwx 1 root root 0 23. Apr 08:28 asus-nb-wmi -> ../../devices/platform/asus-nb-wmi/backlight/asus-nb-wmi

System:
  Kernel: 5.17.1-3-MANJARO arch: x86_64 bits: 64 compiler: gcc v: 11.2.0
    Desktop: Xfce v: 4.16.0 tk: Gtk v: 3.24.29 info: xfce4-panel, plank
    wm: xfwm v: 4.16.1 dm: LightDM v: 1.30.0 Distro: Manjaro Linux
    base: Arch Linux
Machine:
  Type: Laptop System: ASUSTeK product: ZenBook UX425IA_UM425IA v: 1.0
    serial: <filter>
  Mobo: ASUSTeK model: UX425IA v: 1.0 serial: <filter>
    UEFI: American Megatrends v: UX425IA.309 date: 01/29/2021
Battery:
  ID-1: BATT charge: 46.0 Wh (83.6%) condition: 55.0/67.1 Wh (82.0%)
    volts: 15.9 min: 15.9 model: ASUSTeK UM425 type: Li-ion serial: <filter>
    status: discharging cycles: 425
Memory:
  RAM: total: 15.11 GiB used: 2.2 GiB (14.5%)
  Array-1: capacity: 32 GiB slots: 2 EC: None max-module-size: 16 GiB
    note: est.
  Device-1: DIMM 0 type: LPDDR4
    detail: synchronous unbuffered (unregistered) size: 8 GiB speed:
    spec: 4266 MT/s actual: 3733 MT/s volts: N/A width (bits): data: 32
    total: 32 manufacturer: N/A part-no: K4UBE3D4AA-MGCL serial: N/A
  Device-2: DIMM 0 type: LPDDR4
    detail: synchronous unbuffered (unregistered) size: 8 GiB speed:
    spec: 4266 MT/s actual: 3733 MT/s volts: N/A width (bits): data: 32
    total: 32 manufacturer: N/A part-no: K4UBE3D4AA-MGCL serial: N/A
CPU:
  Info: 6-core model: AMD Ryzen 5 4500U with Radeon Graphics bits: 64
    type: MCP smt: <unsupported> arch: Zen 2 rev: 1 cache: L1: 384 KiB
    L2: 3 MiB L3: 8 MiB
  Speed (MHz): avg: 1400 min/max: 1400/2375 boost: enabled volts: 1.2 V
    ext-clock: 100 MHz cores: 1: 1400 2: 1400 3: 1400 4: 1400 5: 1400 6: 1400
    bogomips: 28454
  Flags: 3dnowprefetch abm adx aes aperfmperf apic arat avic avx avx2 bmi1
    bmi2 bpext cat_l3 cdp_l3 clflush clflushopt clwb clzero cmov cmp_legacy
    constant_tsc cpb cppc cpuid cqm cqm_llc cqm_mbm_local cqm_mbm_total
    cqm_occup_llc cr8_legacy cx16 cx8 de decodeassists extapic extd_apicid
    f16c flushbyasid fma fpu fsgsbase fxsr fxsr_opt ht hw_pstate ibpb ibrs
    ibs irperf lahf_lm lbrv lm mba mca mce misalignsse mmx mmxext monitor
    movbe msr mtrr mwaitx nonstop_tsc nopl npt nrip_save nx osvw
    overflow_recov pae pat pausefilter pclmulqdq pdpe1gb perfctr_core
    perfctr_llc perfctr_nb pfthreshold pge pni popcnt pse pse36 rapl rdpid
    rdpru rdrand rdseed rdt_a rdtscp rep_good sep sha_ni skinit smap smca
    smep ssbd sse sse2 sse4_1 sse4_2 sse4a ssse3 stibp succor svm svm_lock
    syscall tce topoext tsc tsc_scale umip v_spec_ctrl v_vmsave_vmload vgif
    vmcb_clean vme vmmcall wbnoinvd wdt xgetbv1 xsave xsavec xsaveerptr
    xsaveopt xsaves
Graphics:
  Device-1: AMD Renoir vendor: ASUSTeK driver: amdgpu v: kernel pcie:
    speed: 16 GT/s lanes: 16 ports: active: eDP-1 empty: DP-1,DP-2,HDMI-A-1
    bus-ID: 04:00.0 chip-ID: 1002:1636 class-ID: 0300
  Device-2: IMC Networks USB2.0 HD UVC WebCam type: USB driver: uvcvideo
    bus-ID: 1-3:2 chip-ID: 13d3:56eb class-ID: fe01 serial: <filter>
  Display: x11 server: X.Org v: 1.21.1.3 compositors: 1: xfwm v: 4.16.1
    2: Picom v: git-60eb0 driver: X: loaded: amdgpu unloaded: modesetting
    alternate: fbdev,vesa gpu: amdgpu display-ID: :0.0 screens: 1
  Screen-1: 0 s-res: 1920x1080 s-dpi: 96 s-size: 508x285mm (20.00x11.22")
    s-diag: 582mm (22.93")
  Monitor-1: eDP-1 mapped: eDP model: AU Optronics 0x403d res: 1920x1080
    hz: 60 dpi: 158 size: 309x173mm (12.17x6.81") diag: 354mm (13.9") modes:
    max: 1920x1080 min: 640x480
  OpenGL: renderer: AMD RENOIR (DRM 3.44.0 5.17.1-3-MANJARO LLVM 13.0.1)
    v: 4.6 Mesa 21.3.8 direct render: Yes
Audio:
  Device-1: AMD Renoir Radeon High Definition Audio vendor: ASUSTeK
    driver: snd_hda_intel v: kernel pcie: speed: 16 GT/s lanes: 16
    bus-ID: 04:00.1 chip-ID: 1002:1637 class-ID: 0403
  Device-2: AMD ACP/ACP3X/ACP6x Audio Coprocessor vendor: ASUSTeK
    driver: snd_rn_pci_acp3x v: kernel pcie: speed: 16 GT/s lanes: 16
    bus-ID: 04:00.5 chip-ID: 1022:15e2 class-ID: 0480
  Device-3: AMD Family 17h/19h HD Audio vendor: ASUSTeK
    driver: snd_hda_intel v: kernel pcie: speed: 16 GT/s lanes: 16
    bus-ID: 04:00.6 chip-ID: 1022:15e3 class-ID: 0403
  Sound Server-1: ALSA v: k5.17.1-3-MANJARO running: yes
  Sound Server-2: JACK v: 1.9.20 running: no
  Sound Server-3: PulseAudio v: 15.0 running: yes
  Sound Server-4: PipeWire v: 0.3.49 running: yes
Network:
  Device-1: Intel Wi-Fi 6 AX200 driver: iwlwifi v: kernel pcie: speed: 5 GT/s
    lanes: 1 bus-ID: 01:00.0 chip-ID: 8086:2723 class-ID: 0280
  IF: wlp1s0 state: up mac: <filter>
  IP v4: <filter> type: dynamic noprefixroute scope: global
    broadcast: <filter>
  IP v6: <filter> type: dynamic noprefixroute scope: global
  IP v6: <filter> type: noprefixroute scope: link
  IF-ID-1: virbr0 state: down mac: <filter>
  IP v4: <filter> scope: global broadcast: <filter>
  WAN IP: <filter>
Bluetooth:
  Device-1: Intel AX200 Bluetooth type: USB driver: btusb v: 0.8
    bus-ID: 1-4:3 chip-ID: 8087:0029 class-ID: e001
  Report: rfkill ID: hci0 rfk-id: 0 state: up address: see --recommends
Logical:
  Message: No logical block device data found.
RAID:
  Message: No RAID data found.
Drives:
  Local Storage: total: 491.38 GiB used: 92.51 GiB (18.8%)
  ID-1: /dev/mmcblk0 vendor: Apacer model: APPSD size: 120 MiB type: SSD
    serial: <filter> scheme: MBR
  ID-2: /dev/nvme0n1 vendor: Kingston model: OM8PCP3512F-AB
    size: 476.94 GiB speed: 31.6 Gb/s lanes: 4 type: SSD serial: <filter>
    rev: ECFK52.3 temp: 32.9 C scheme: GPT
  ID-3: /dev/sda type: USB vendor: SanDisk model: Cruzer Fit
    size: 14.32 GiB type: N/A serial: <filter> rev: 1.00 scheme: MBR
  Message: No optical or floppy data found.
Partition:
  ID-1: / size: 67.16 GiB used: 60.26 GiB (89.7%) fs: ext4
    dev: /dev/nvme0n1p5 label: N/A uuid: 22f0c4b8-545a-4076-b456-15baadaf5d71
  ID-2: /boot/efi size: 96 MiB used: 27.3 MiB (28.5%) fs: vfat
    dev: /dev/nvme0n1p1 label: N/A uuid: 0056-1362
  ID-3: /home size: 135.33 GiB used: 32.23 GiB (23.8%) fs: ext4
    dev: /dev/nvme0n1p6 label: N/A uuid: 9ee8efbe-95d9-4817-b05a-dff5906ff21f
Swap:
  ID-1: swap-1 type: partition size: 7.81 GiB used: 0 KiB (0.0%) priority: -2
    dev: /dev/nvme0n1p7 label: N/A uuid: 24373f4d-1c4e-4877-899c-d6542f1fa56c
Unmounted:
  ID-1: /dev/mmcblk0p1 size: 119.3 MiB fs: vfat label: N/A uuid: A87B-A154
  ID-2: /dev/nvme0n1p2 size: 16 MiB fs: N/A label: N/A uuid: N/A
  ID-3: /dev/nvme0n1p3 size: 257.41 GiB fs: ntfs label: N/A
    uuid: 6ED6E53FD6E50863
  ID-4: /dev/nvme0n1p4 size: 587 MiB fs: ntfs label: N/A
    uuid: F0FC34F3FC34B626
  ID-5: /dev/nvme0n1p8 size: 4 GiB fs: ntfs label: DRIVERS
    uuid: 7C3C9F8C3C9F4056
  ID-6: /dev/sda1 size: 14.32 GiB fs: vfat label: N/A uuid: 8130-7A13
USB:
  Hub-1: 1-0:1 info: Hi-speed hub with single TT ports: 4 rev: 2.0
    speed: 480 Mb/s chip-ID: 1d6b:0002 class-ID: 0900
  Device-1: 1-3:2 info: IMC Networks USB2.0 HD UVC WebCam type: Video
    driver: uvcvideo interfaces: 5 rev: 2.0 speed: 480 Mb/s power: 500mA
    chip-ID: 13d3:56eb class-ID: fe01 serial: <filter>
  Device-2: 1-4:3 info: Intel AX200 Bluetooth type: Bluetooth driver: btusb
    interfaces: 2 rev: 2.0 speed: 12 Mb/s power: 100mA chip-ID: 8087:0029
    class-ID: e001
  Hub-2: 2-0:1 info: Super-speed hub ports: 2 rev: 3.1 speed: 10 Gb/s
    chip-ID: 1d6b:0003 class-ID: 0900
  Hub-3: 3-0:1 info: Hi-speed hub with single TT ports: 4 rev: 2.0
    speed: 480 Mb/s chip-ID: 1d6b:0002 class-ID: 0900
  Device-1: 3-2:2 info: SanDisk Cruzer Fit type: Mass Storage
    driver: usb-storage interfaces: 1 rev: 2.0 speed: 480 Mb/s power: 200mA
    chip-ID: 0781:5571 class-ID: 0806 serial: <filter>
  Hub-4: 4-0:1 info: Super-speed hub ports: 2 rev: 3.1 speed: 10 Gb/s
    chip-ID: 1d6b:0003 class-ID: 0900
Sensors:
  System Temperatures: cpu: 35.0 C mobo: N/A gpu: amdgpu temp: 36.0 C
  Fan Speeds (RPM): cpu: 0
Info:
  Processes: 281 Uptime: 24m wakeups: 3238 Init: systemd v: 250 Compilers:
  gcc: 11.2.0 clang: 13.0.1 Packages: 1649 pacman: 1646 snap: 3
  Shell: Bash (sudo) v: 5.1.16 running-in: xfce4-terminal inxi: 3.3.15


found out that my system had two conflictiung backlight devices.

i had to pass acpi_backlight=native on the kernel command line.

after that only one backlight device is registered.

ls /sys/class/backlight/
amdgpu_bl0

backlight control now works again.