If EFS is dead and no backup exists, try these in order:
The J710F EFS file is a critical component of Samsung's Android-based smartphones, particularly those running on the Android 4.4 KitKat operating system. EFS, short for Encrypted File System, is a file system used by Samsung to store sensitive information such as IMEI (International Mobile Equipment Identity) numbers, product codes, and other device-specific data. j710f efs file