int LED = 2;
int btn = 27;

void setup() {
  // put your setup code here, to run once:
  pinMode(LED, OUTPUT);
  pinMode(btn, INPUT_PULLUP);
}

int btnState;
void loop() {
  btnState = digitalRead(btn);
  if (btnState == LOW) {
    digitalWrite(LED, LOW);
  } else {
    digitalWrite(LED, HIGH);
  }
  
}