Solution to everything turning to questionmarks.

This is not a question and I hope that is alright.

My company had a user where his new Macbook got only questionmarks from the login screen to the normal UI.

After some research it was a font cache that was corrupt. For anyone looking for that sollution please look below:

Close all running applications. From an administrator account, open the Terminal app and enter the following command. You can also copy/paste it from here into the Terminal window:

sudo atsutil databases -remove

Terminal will then ask for your admin password. As you type, it will not show anything, so be sure to enter it correctly.

This command removes all font cache files. Both for the system and the current logged in user account. After running the command, close Terminal and immediately restart your Mac.

I hope this helps anyone.