Keyboard and Trackpad behave erratic MacBook Pro 13 (early 2015) i have a slight problem with my MacBook Pro early 2015. For some reason the keyboard strokes are not correctly registered by the OS. On the login screen typing either triggers the “can’t type here” sound or wrong letters / erratic movement occur. For example pressing the louder button usually first turns the sound down twice and then mutes the Mac. Also a trackpad click only triggers the secondary click. A normal click or tap is not possible. The same stays true after login.

This is already weird but I also checked the virtual keyboard and there the right buttons are highlighted on stroke meaning that at least there I see full function. Also the Option + keys correctly types each special symbol. Also weird is that on the virtual key the acute is always lid in orange. Sometimes the keyboard completely works for some time just to revert to the no-function a little later. What i also noticed is that I can trigger the failure the following way: 
if the keyboard works the acute on the virtual keyboard is always lid. If I press the left shift key, the acute is not lid anymore and the keyboard strokes are not recognised by the system anymore. However, the virtual keyboard is still recognising everything just fine.

The error is also present when booting from an USB stick. P+R+Option+Alt does not work and neither does triggering the recovery mode.

What did I try to fix it:

Warranty has run out, therefore I thougt: go for it!

I already exchanged the cable that connects the trackpad to the logic board, I reinstalled the OS, exchanged the trackpad itself and cleared the nvram. I do not know where to look for error reports or such. Thus any pointer would be highly appreciated.

I'd be super happy and grateful if someone could help me!
The keyboard was broken. Apparently very little amounts of liquid can completely brake it. After exchanging the top case/keyboard everything works like a charm.