XPS 9570 internal keyboard issues, no ^and no Str+Alt+T

Hi,

XPS 9570, internal keyboard issues: neither ^ nor Str+Alt+T are recognized (german keyboard). 

Dual boot with WINDOWS and Ubuntu - same problem on both OS.

In WIN hat key sometimes works - extremly slow, like honey.

No problems when using external USB-keyboard (which is what I'm doing here).  

BIOS updated to 1.27.0, drivers updated  - no effect.

Problem may be related to my battery replacement (new one is Dell).

Tried disconnecting the battery and pressing start button several times, then restarting. No effect.

*sigh*

Any suggestion, help would be appreciated.

Best,

Johnny