Even after several hours in full sun my Whisperer looks dead and does not send any signal.
Shirt or long pushes on the button does not change anything.
I suppose that while not that old I have to buy a new one.
Thanks for your advice
Please try leave the sensor under direct sunlight for several more days.
If you have traditional incandescent bulb lamp, you can also put the sensor solar panel closely under the incandescent bulb for severl days.
Please let us know if the sensor still not get charged after a week.