// by Ido Gendel, 2020
// For the Arduino Nano ("Old bootloader")

#define SWITCH_REF_PIN A0
#define SWITCH_IN_PIN A1
#define LIGHT_IND_PIN 13
#define LIGHT_CTRL_PIN 2
#define BUZZER_GND_PIN 11
#define BUZZER_OUT_PIN 12

uint8_t isOpened = 0;
uint8_t n;

//=========================================================
void setup() {

  // Switch is N.C. 
  pinMode(SWITCH_REF_PIN, OUTPUT);
  pinMode(SWITCH_IN_PIN, INPUT_PULLUP);

  pinMode(LIGHT_CTRL_PIN, OUTPUT);
  pinMode(LIGHT_IND_PIN, OUTPUT);

  pinMode(BUZZER_GND_PIN, OUTPUT);
  pinMode(BUZZER_OUT_PIN, OUTPUT);
  
}

//=========================================================
void waitToOpen(void) {

  // Lights Off
  digitalWrite(LIGHT_CTRL_PIN, LOW);
  digitalWrite(LIGHT_IND_PIN, LOW);

  while (HIGH == digitalRead(SWITCH_IN_PIN)) {
  }

  delay(50); // Debounce
  
  isOpened = 1;
  // Lights On
  digitalWrite(LIGHT_CTRL_PIN, HIGH);
  digitalWrite(LIGHT_IND_PIN, HIGH);

}

//=========================================================
void openedWait(uint32_t ms) {

  uint32_t timeStamp = millis();

  if (0 == isOpened) return;

  while (millis() - timeStamp < ms) {
    
    if (HIGH == digitalRead(SWITCH_IN_PIN)) {
      isOpened = 0;  
      break;
    }
    
  }
  
}

//=========================================================
void beep(const uint16_t freq, const uint32_t ms) {

  if (0 == isOpened) return;
  tone(BUZZER_OUT_PIN, freq);
  openedWait(ms);
  noTone(BUZZER_OUT_PIN);
  
}

//=========================================================
void loop() {
  
  waitToOpen();
  openedWait(5000);
  for (n = 0; n < 3; n++) {
    beep(4000, 500);
    openedWait(1000);
  }  

}

https://drive.google.com/file/d/1NYLGT5MHHoqzMJRANOdAMuqTsrBZAlPl/view?usp=sharing