When this is happening during these moments, I cannot log-in nor turn the computer off simply by waiting. I suppose it's f2, because you can do it in Ubuntu pressing f2.

But it turns out that sometimes when turning the computer of, some mysterious key is also pressed, making the splash screen of my system and a screen showing what's happening behind the scenes rapidly toggle between each other. I learned about xinput to disable the keyboard and these inconvenient events, then using an external one. Everything I selected with one click was being deleted and, when in a text editor software or anything that have an input field, all being erased, just like holding the return or backspace key. Few days later, the return started to suffer the same thing. I then removed the button and the small rubber that makes the contact with the board. Two keys, minus and asterisk from the num pad were being pressed and held at random moment when typing something somewhere. My notebook's keyboard suddenly went all paranormal activity like weird.

How to disable your laptop keyboard