Occasional motion detection shows blank screen

I've had this device for about three days now and it is above the garage. Most times it records motion and people with the video and audio working just fine. Live video works just fine. But twice the screen is black without sound as it plays back. One time occurred at 6:30 PM yesterday and another at 11:00 today. It also did not notice when I drove into the garage. Motion is set at default. My RSSI value is -58 and green. I called support and she and I each rebooted the device. I could not get on a ladder during the call to remove the battery. Any ideas? I will try the battery tomorrow when I have some help Paul