Dear Samsung Member,
Greetings from Samsung Customer Support!
To resolve "Brightness " issue kindly follow the given below steps:
1. Perform reset settings:-Settings >General management >Reset >Reset settings.
2. Reset the device:-Kindly create data backup of your device via SMART switch mobile application or http://www.samsung.com/in/support/smartswitch pc suite.
>>Tap on Settings>Tap on General Management>Tap on Reset.
If the issue still persist, kindly register your concern in Samsung Members app (Samsung Members app > Get help > Feedback > Error report).
Note: Please send device log files within 15 minutes of issue occurrence along with the exact issue details.
Thank you for writing to Samsung.
Samsung Customer Support