Asus TUF GAMING FX504GD strange keyboard problem

[deim31]

Hi, I have Asus TUF GAMING FX504GD Laptop and noticed this problem:
After boot windows 10 there is "welcome" screen with time etc.
Laptop automatically presses minus key on num block - it displays windows login input which is started to fill with minuses.
It persists until any key is pressed.
After login to Windows I'm running e.g. Notepad.
When I press minus key on num block nothing is typed key seem dead.
But when I press Ctrl+Shift or Ctrl+Alt it start to write minuses endlessly until I press any other key.
Now I tried to press some combinations and mentioned behavior is triggered by Ctrl+Shift+Alt or Ctrl+Shift+Ctrl.
I've tried to reseat KB cable and reset BIOS no help so far.
It happens in Linux also so It's not OS related problem.
Don't know what happens - is only minus key bad or full keyboard or?
Thanks

 

[deim31]

I've just removed cap nad X holding system under it and tried to test microswitch under cap and it doesn't get any response in Keyboard Test Utility.
Will removing of this microswitch solve the issue or is it elsewhere? I think I can live without extraction (minus) key - auto typing minuses is horrible.