You're looking for a report on SPD Android IMEI repair codes. Here's some information:

In many modern Android versions, direct dialer codes have been disabled for security reasons. If the codes do not work, technicians typically use PC-based tools such as SPD Research Tool (Spreadtrum Flash Tool) or Miracle Box . These tools write the IMEI directly to the device's NV (Non-Volatile) memory via a USB connection in "Flash Mode" or "Diag Mode."