For those of you with Linear garage door controllers. When the sensor stops responding the device goes to a stopped state. Working with tech support, the sensor has a pairing/activate button held depressed by the back panel. When I removed mine I left the back panel mounted to the door. This is where the fun began. Thinking the button was only for pairing, I replaced the battery. Pushed the button. And thought all was well. Not the case. The button has to remain depressed. Hence the little nub on the back panel. So lessons learned and information to share. Remount the sensor after the battery change and push the pair button on controller. The sensor will repair and work prior to the condition that stopped the device. Thanks to all the tech support who worked this problem.