   if(currentMillis - previousMillis > interval) {
     previousMillis = currentMillis;   
     checkRelay();
-    Serial.println(checkDoor() + ":" + checkMotion());
+    Serial.println(checkDoor() + ":" + checkMotion() + ":" + checkButton());
     digitalWrite(ledPin, ledState);
   }
 }

  digitalWrite(pirPin, LOW);
  pinMode(relayPin, OUTPUT);
  digitalWrite(relayPin, HIGH);
  //delay(20000); // Wait for PIR to warm up
  Serial.begin(9600);
}

String checkDoor() {

const int sensorPin =   2;      // the number of the door sensor pin
const int pirPin =      3;      // the number of the motion detector pin
const int relayPin =    4;      // the number of the door opening relay pin
const int buttonPin =   5;      // the number of the button switch pin


// Variables will change:
