Most MT6580 phones max out at Android 7.0. If you have a custom Android 8/9 ROM (like LineageOS 15.1), the AT command still works if the kernel has the pttycmd interface. Otherwise, use SN Writer.
Relying on a dialer code for MT6580 IMEI repair is a waste of time. It is an obsolete method. mt6580 imei repair code