Samsung A series Service Solution

The problem has been identified.

The EFS Folder, which contains your device IMEI, Baseband version , controls bandwidth etc. Has been deleted or corrupted.

Which means no mobile data or calls or message.

And shows a message in recovery mode

 (Vol Up + Power + Home)

"Dm-verity failed"

Fix -

If EFS exists but corrupted , try flashing stock firmware .

If deleted, you need to give to Service center/Customer center.

They will perform a hard reset and install stock firmware and also latest Android

 version totally wiping data and cache too.

And will assign new IMEI number and new EFS folder.

So perform a full backup before proceeding.

The OS installation Guide Is In Our Previous Post

Installing Without Guide Can Destroy Your Device 

Thanx