const int BTN_ON  = 12; // Pull-up:   Presionado => LOW
const int BTN_OFF = 3;  // Pull-down: Presionado => HIGH

void setup() {
  Serial.begin(115200);
  pinMode(LED_BUILTIN, OUTPUT);
  pinMode(BTN_ON, INPUT);
  pinMode(BTN_OFF, INPUT);
}

void loop() {
  int est_on = digitalRead(BTN_ON);
  int est_off = digitalRead(BTN_OFF);
  if(est_on == LOW) { // on presionado?
    digitalWrite(LED_BUILTIN, HIGH);
    Serial.println("LED PRENDIDO");
  }
  if(est_off == HIGH) { // off presionado?
    digitalWrite(LED_BUILTIN, LOW);
    Serial.println("LED APAGADO");
  }
}