Fixed GPU-deactivation but Wi-Fi is not working and textmode remains
Partial answer addressing the "textmode" (verbose boot) problem:

What you called "textmode" in an earlier version of your question is really the verbose boot mode. There is nothing special or malicious or negative about it. Within the tutorial it is just employed to make it easier to get to know immediately the point of failure during boot should anything go wrong with the tutorial.

If you followed the tutorial it is to expected to be there. If everything works and if you do not like the aesthetics of it:

type in Terminal:

  nvram -p


that should output something like: 

 boot-args  -v 


To get rid of this "textmode", you need tot type 

sudo nvram boot-args=" "


Confirm its deletion with another nvram -p and see thge parameter -v for the boot-args gone. Next boot should then be graphical again.