I have a DS-7604I1 series NVR which is 10 months old, and I upgraded the firmware. The reason I upgraded the firmware was that of my four cameras, only two would allow me to replay videos from intrusion detection alarms. The message said that it cannot play video in specified time, which was only about two seconds. They play motion detection videos just fine, and the other two cameras play intrusion detection videos as they should. After the upgrade,I went to enable the intrusion detection on the first two cameras, but the option to do so for smart events has vanished from the options. I wish I could reverse the upgrade but don't know how to do so, or if that would help. Any thoughts please?