I have an HTC Evo Shift. I turned down my brightness & then got a text. I answered the text then locked my screen. I tried to unlock it and it just would not turn back on. The start-up screen came on but as soon as the "4g" thing came on about to go to the lock screen, the screen dimmed out & turned black. I've tried everything & i don't know how to fix it. PLEASE HELP?!