Dear Samsung Member,
Greetings from Samsung Customer Support!
As per your concern, we would request you to kindly perform the following steps to resolve your issue.
1. Go to Settings>>Display>>Adjust the brightness.
2. You can check the device in safe mode and for the same mode you can tap on the given link. https://www.samsung.com/in/support/mobile-devices/safe-mode-on-samsung-phones/
3. Update device software: Settings >> Software update >> Download and install.
4. Reset the device.
Note: Kindly create a data backup of your device via the smart switch mobile application or http://www.samsung.com/in/support/smartswitch pc suite.
Remember the Google password before resetting the device because it is required during the initial setup.
If you do not remember then advise to reset (Forgot password) the Google account.
5. For this; Open Gmail (https://accounts.google.com/servicelogin)>>Select forgot password>>Select "try another way" like mobile number, security question, etc.>>Select Next>>Enter a new password>>Tap on Next.
6. Apps>settings> general management>reset (Reset your device to its factory default settings. This will erase all data, including files and downloaded apps.)
Also share report the problems with a log file. To share a log file, click on the Samsung Members Application (Open Samsung Members Application > Support> Tap on error report > Type your query > Send).
Samsung Customer Support