Upgrade the mobile phone system to the latest, then turn it off and restart it to see if there is a screen.
2. Turn off the automatic adjustment function of mobile phone screen brightness, as follows:
1. First, click "Settings" on the desktop of the iPhone 6s.
2. Then select the "General" option in the setting interface of the mobile phone.
3. Then open "Auxiliary Functions" in the common interface to enter.
4. Click the "Display Adjustment" option after entering.
5. Finally, turn off the switch in the column of "automatic brightness level", as shown in the figure.
Third, take your mobile phone and warranty card to the nearest Apple official mobile phone repair center for repair.