A firmware update was recently released for the NVR6XX-4KS2 series devices.
Information, instructions, and download links can be found Here
Software/Change ONVIF Password via ONVIF Device Manager
From Dahua Wiki
Change ONVIF Password via ONVIF Device Manager
- A computer capable of viewing live-streaming video(s)
- An internet Connection or LAN capable of viewing live-streaming video(s)
- Access to a the NVR
- Login Credentials for the NVR
- Onvif Device Manager installed
Step by Step Instructions
1. Login into ONVIF Device Manager.
2. Select device for password to be modified.
3. Click on "User Management".
4. Click on a User to to be Modified -> Click on Modify.
5. Choose and input a User Name and Password.
6. Choose a role for the User Name and Password you have created.
7. Click "Apply" to save.