Dahua DHI-NVR5208-4KS2 User Manual page 336

 When you see corresponding dialogue box "System is shutting down..." Do not click power
on-off button directly.

Do not unplug the power cable or click power on-off button to shutdown device directly when
device is running (especially when it is recording.)

Shut down the device and then unplug the power cable before you replace the HDD.
Operations

From the main menu (Recommended)
Step 1 Click
Step 2 Select Shutdown.
Draw the unlock pattern or input password first if you have no authority to shut down.
See Figure 4-260 or Figure 4-261.
at the top right corner. See Figure 4-259.
Figure 4-259
Local Basic Operation 325