That was in the instructions that I didn't read. Something about the brief red glow as you turn it off. I think if you get the glow....you're good to go.

USB charging is great. Finally, all of my lights, Bluetooth speaker, camera and of course phone are USB rechargeable. Oh yeah--so are the tent lights and my little camping fan. I bought a Surface 3 because it's USB rechargeable. All fine and good so long as there's a power source. Two Anker solar chargers, each charging a 15,000mha battery and one other thing has never let me down. Free power, just keep the batteries goin' for sunless times!!