The charger you use MUST be 5V / 2amps to get the lightning bolt. Anything less than 2amps and you will get the red X. I had experimented with about ten different chargers with amperage outputs from 0.5, 0.7, 1.0, 1.2, 1.5 and 2.0. The only one that worked was the one with 2.0amps. Use the wall...