1）When the NVR is turned on and does not work normally, please power it off and uninstall the hard drive and unplug network cables. Reboot it and try restoring factory setting, Here is how: System Setup--System Admin--Factory setting---Apply.
2) If the NVR works fine when turned on, please tryA: Upgrade the version to the latest.
B: Navigate to System Setup--General Setup--Error Setup: check whether you have enabled "Alarm" or "Buzzer". If you have, please cancel the tick to disable.
C: Check the upper right corner of screen and check whether there is a sign of person that may trigger motion detection. If alarm or buzzer is not needed, please cancel the tick before them. Here is how: System Setup--Channel Setup--Video Detection.