1. Network problem: Please ensure that the device is connected to a stable Internet network. Try using another application or opening a webpage to confirm whether the network connection is normal.

2. System problem: Sometimes the application will fail or make an error, resulting in login failure. You can try to restart your device and make sure that you are using the latest version of the Le Di robot application. The problem still exists. You can try to uninstall and reinstall the application, or contact the technical support team of Le Di Robot for further assistance.

3. Account number problem: the account number is abnormal, and the login failed. Please make sure that the user name and password entered are correct and there are no spelling mistakes. If you forget your password, you can use the Forgotten Password option to reset it.