What should I do if the Brightown HLS-W-XXXWW-S LED Solar Firefly Light won't turn on?

The most likely cause is insufficient sunlight, so you should place the light in a sunnier location and ensure the solar panel receives at least 6-8 hours of direct sunlight. You can also try charging it via USB and verify that the power switch is in the ON position. (Pages 5, 7, 9)