There are many possible causes of this problem. To solve it, please try the following:
- Please check if the light sensor is blocked. When the light sensor is blocked, your phone will not be able to adjust the screen brightness automatically.
- Please enter Settings > Display > Brightness, and check if Automatic brightness is turned off. If it is, your phone will not be able to adjust the screen brightness automatically.
- Please restart your phone.
- Please back up important data and restore your phone to factory settings or update it to the latest version, as deleting system files by mistake could mean the screen is unable to adjust brightness automatically.
- If the problem persists after you have carried out the steps detailed above, please back up important data and take the receipt issued with your phone to an authorized Huawei service center for repair.