…
  // begin initialization
  if (!BLE.begin()) {
    Serial.println("starting BLE failed!");

    while (1);
  }

  Serial.println("BLE Central scan");

  // start scanning for peripheral
  BLE.scan();

  // …

  BLEDevice peripheral = BLE.available();

  if (peripheral) {
    // ...

    Serial.println("Connecting ...");

    if (peripheral.connect()) {
      Serial.println("Connected");
    } else {
      Serial.println("Failed to connect!");
      return;
    }

    // discover peripheral attributes
    Serial.println("Discovering attributes ...");
    if (peripheral.discoverAttributes()) {
      Serial.println("Attributes discovered");
    } else {
      Serial.println("Attribute discovery failed!");
      peripheral.disconnect();
      return;
    }

    BLEService batteryService = peripheral.service("180f");

    if (batteryService) {
      // use the service
      BLECharacteristic batteryLevelCharacterisic = peripheral.characteristic("2a19");

      if (batteryLevelCharacterisic) {
        // use the characteristic
      } else {
        Serial.println("Peripheral does NOT have battery level characteristic");
      }
    } else {
      Serial.println("Peripheral does NOT have battery service");
    }

    // ...
  }
…