void setup() {
  // Start Serial communication at 9600 baud rate
  Serial.begin(9600);

  // Set the onboard LED pin (Pin 13) as output
  pinMode(LED_BUILTIN, OUTPUT);
}

void loop() {
  // Check if data is available in the serial buffer
  if (Serial.available() > 0) {
    String command = Serial.readString();  // Read the incoming string

    // Check if the received command is "OFF"
    if (command == "OFF") {
      // Turn off the onboard LED
      digitalWrite(LED_BUILTIN, LOW);
    }
  }
}