So i just realized today that the camera flash will not work when the battery is under 24%. HTC confirmed this after 3 phone calls to them as did I. I monitored the battery and when it was at 24% the flash worked with the camera. It does not matter if battery saver is on or off , nor does it matter if the phone is charging. I find this a bad feature I should be able to drain my battery if want to. My HTC HD7 did not exhibit this behavior. It just does not make sense and only makes me feel more like i always have to have it charged.