It's very simple. Double click the S pen above the screen. U will get the smart screen with different options. Select SCREEN WRITE that will capture the complete screen and u can save it.
you can try hold Home + Power, does it work?
If hot, try to use 3rd party screen capture like https://forums.androidcentral.com/e...com.icecoldapps.screenshoteasy&token=wfyNR8bO
Br