If you can share (e.g., flash failed, dropped phone) or what the IMEI shows in settings , I can provide a more tailored answer.
While older methods required complex boxes, many modern solutions like SamDevs or tools like ChimeraTool allow for "Repair + Patch Certificate" procedures. Standard Repair Checklist: c7100 imei repair
| Error Message | Cause | Solution | |---------------|-------|----------| | S_BROM_CMD_STARTCMD_FAIL | USB driver issue | Reinstall MTK VCOM drivers, disable driver signature enforcement. | | Write IMEI fails – NVRAM full | Corrupted NVRAM size | Use Miracle Box to format NVRAM first. | | Baseband Unknown | Lost modem firmware | Reflash stock firmware (only modem.img or NON-HLOS.bin ). | | Invalid IMEI after repair | Checksum mismatch | Use Miracle Box’s “Fix Checksum” option. | If you can share (e