Keyboard and trackpad not active when OS is loaded.

Hi everybody,

After two days of testing and searching the internet, I have not yet been able to find a cause.

The situation: the keyboard and trackpad stopped working overnight. When booting in a different mode - if the OS has not yet loaded - both work. Finally did a clean install, but that doesn't help either.

Just discovered EtreCheckPro and, with full disk access, did a check. There are no malfunctions.

Who can clarify: is it a hardware problem, for example the motherboard? Or is it a software problem, for example a driver not loading?

And above all of course: how do I get the Macbook working again? (Without the Bluetooth devices I'm using right now.)

Greetings and thanks in advance!

Dees