If your vehicle is showing push-button start does not respond when pressed, here are the most likely causes and the parts you'll need to fix each one.
The vehicle's immobilizer cannot detect the smart key because the battery inside the fob is dead, preventing the start sequence from initiating.
The main vehicle battery lacks the necessary voltage to power the starter motor and the vehicle's electronic control modules.
Push-button start systems require the brake pedal to be depressed. If the brake light switch fails, the computer doesn't know you are pressing the pedal and will only cycle the accessory power.
Poor connections at the battery prevent sufficient amperage from reaching the starter. This is highly common after recent battery replacement or maintenance.
The push-button successfully sends the start command, but the starter motor itself is worn out, seized, or has a failed solenoid.
The vehicle's computer must confirm the transmission is in Park or Neutral before allowing the engine to crank. A failed switch prevents this confirmation.
The physical start button or its internal electrical contacts have worn out and are no longer sending a signal to the vehicle's computer.