@livfe what you are describing does not sound like a settings issue. A wrong keyboard setting would not turn into a "go-no go" situation. It would be either one at all times. This could be a bad keyboard matrix or keyboard controller. I would try to replace the keyboard.
Since iFixit does not yet have a specific guide for that, try something like [https://www.laptopkeyboard.com/installation-guides/toshiba/satellite/a665-s5170/|this video]