Why is My Chromebook Going Full Screen?

Carl is having a Chromebook issue where he's typing, the tab and address bars will disappear. It goes full screen. Leo says to use the keyboard combination Alt "-" to reset it. Also check the function keys, like F11. He may strike the wrong one and boom, he's in full screen. That's likely the issue. Carl also powerwashed his Chromebook and he can't log into his network because the keyboards reset. Leo suspects that Carl may have a faulty or damaged keyboard.