Sometimes flashing generic firmware erases the IMEI (network identity). Only flash region-specific firmware. If lost, you need a “Modem Meta” tool to rewrite the IMEI from the box label.
Disclaimer: Flashing firmware carries inherent risks, including voiding your warranty. The author is not responsible for bricked devices. Always ensure you have the correct regional firmware for your specific model number (e.g., ZTE 9042N). ZTE Blade V40 Design Firmware