Received as gift early December 2017. Worked well for 2 months, then base lost connection with sensor. I have removed the batteries and power supply. Then installed new batteries in sensor and saw the long flash red light followed by short flashes every 30 to 40 seconds. Then connected power supply to base unit. Actually established a connection the first try, waited 15 minutes, moved sensor 20 feet away and lost wireless connection. Repeated the process several times but never connected again. Sensor continues to flash, but that's all. Help, please?