Just extract the attached archive (dmtf.rar) in:
Your device must be unlocked. Full FS access has to to be activated.
2. Back-up Whatsapp Conversations
Then connect your phone to the PC* and go to:
and copy the "Backup" folder in your PC or SD-Card.
Next time you hard reset you can re-place the folder to restore the messages.
*Your phone has to be unlocked. Full FS access has be activated.