What is the and current firmware string listed on your router's status page? Who is your internet service provider (ISP) ?
This is usually because the file is corrupted or not intended for your specific F680 model (e.g., V4 vs. V1). Ensure the model number matches exactly. Zte F680 Firmware
Sometimes, you may need to manually flash firmware—for example, if you bought a used ONT from a different ISP or if you want to unlock advanced settings (like changing the Wi-Fi country code or bridging ports). What is the and current firmware string listed