2) If the NVR works fine when turned on, please try
A. 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.