Return to the manufacturer OS using exact stock images and relock only after a complete verified restore.

Prepare before failure

Download or bookmark the official stock restore method before flashing a custom ROM. Record the exact model, region, firmware channel and bootloader revision.

Keep backups of personal data outside the phone; stock restore normally wipes the device.

Restore completely

Use the manufacturer’s official factory image, full OTA, rescue tool or documented flashing package. Restore all required boot-critical and vendor partitions, not only system.

Boot stock Android successfully, complete any required firmware update and verify cameras, radio and updates before considering relock.

Relock rule

Relock only when the device is running a complete, correctly signed image set that the bootloader accepts. Relocking mismatched or modified partitions can make the device unbootable and usually wipes data again.

A Samsung Knox Warranty Bit or similar permanent state does not reset simply because stock firmware is restored.

Critical safety boundary

Unlocking and flashing can erase data, weaken device security, disable protected services or make a phone unbootable. Use only your own device, exact model-specific instructions and a tested stock restore path.

Official and primary sources

35 · Custom ROMs and Android System Modding

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