Use APKPure App
Get imeiRepairTool old version APK for Android
You can easily backup your efs(like imei,mac adress,serial number etc.)folder.
This program useful for backup your efs folder.
When your imei show Null/Null or imei starting 0049 you can easily repair your imei.
Our program working every Samsung Galaxy devices.(Tested).
This program need some root permissions.
We are not responsible any problems.