Only people with the red key make it to computer core.

The elevator is musical instrument. Maybe you could fool Ronny with your own red key.

What musical instrument also has keys in it?

The piano at Goal's habitat. You can borrow one of the keys in it.

Use a tool, tool.

Take the coal tongs by the fireside and use them on the grand piano. You have a key.

Maybe you could wrap it in some kind of red skin.

You couldn't do wurst.

There is the Wurst-Things-Wurst machine in the cocktail bar (Chill-out zone). Stick the white key into it. It is now reddish.

Yes, Ronny says it has to be more red.

Maybe heating it up a little would make it more red.

There is a heating lamp at the petting zoo heating the chickens. Show the sausage key to the lamp.

Indeed. Now you can put it in the empty slot and play it with the mallet. Ohh... how red does it sound.