Having had the solar panel people in to move the isolators in the garage slightly, so out of the way of the car mirror, the energy monitor is no longer giving a reading. The red light on the transmitter was flashing, which I assumed meant a low battery. I've replaced those, pressed the reset button, but no lights, no nothing.
I can't find the instructions but remember pressing the up and down buttons together to pair them up. I've got them both together in the kitchen but they're not talking.