: Any manual modification or backup of the EFS partition requires Root privileges to access the protected system directory. Last Resort

In many regions, changing or repairing an IMEI is subject to strict local laws. Ensure you are only restoring the device's original identity.

For severe corruption where no backup exists, technicians use hardware boxes like Z3X or Octoplus to "Repair IMEI" or "Write Cert" files to the EFS partition.

Do you have or a custom recovery (TWRP) installed?

Without the EFS file, your IMEI becomes null, rendering the phone incapable of making calls or sending SMS.