If the dialer codes do not work or the Engineering Mode is locked, you can use PC-based utilities designed for MediaTek devices:
Occasional system-level crashes can trigger a reset of the baseband parameters. Alternative Tools for MT6580 IMEI Repair mt6580 imei repair code
A lightweight official MediaTek tool specifically for writing Serial Numbers and IMEIs. If the dialer codes do not work or
Note: If you get an "AT command is failed to send" error, put a space between AT and + (e.g., AT +EGMR ). Restart your device to save the changes. Why is your MT6580 IMEI "Invalid"? mt6580 imei repair code
The professional choice for MTK devices. It allows you to write IMEI directly to the NVRAM in "Meta Mode."