If there is no light when you press the button, the sensor is completely out of battery. We suggest you continue leave the sensors under direct sunlight for several more days to charge. If the weather not good, it may takes longer time.
If you have incandescent bulb light at home, you can also charge it under your incandescent light, make sure the light bulb is close to the solar panel.
It takes some time for our R&D to look into the questions and check the user account. We have replied to the posted questions now. You can also directly send us email to firstname.lastname@example.org with your Netro account registered email.