No. Just do the su command on its own first (literally two letters 'su' and hit enter) and grant root when it asks.
Then type the whoami command, hopefully you will be root or 0 or something.
Then do echo 1 > /sys/class/dp_sec/dex
And so on.
---------- Post added at 03:22 PM ---------- Previous post was at 03:20 PM ----------
Wait, you did do it once correctly.
When it is successful it will not say anything.
You can check by going 'cat /sys/class/dp_sec/dex' and hopefully it will be 1 without being connected to DeX. Now try to launch the DeX activity, try using the quick shortcut maker app.
It seems like the phone does not have the right settings to fit the screen or something. when I spam the Dex application button, sometimes I see a black screen like if it's trying to launch the app, and one time I had a
landscape orientation black screen, so we're almost done I guess.