This evening, after turning off my S4, then attempting to restart, my screen was totally black. Nothing I did would turn on the phone. I thought the battery might have been the problem, so I swapped batteries with another S4; no change. Attached the phone to a standard charger, with no change in results. Screen constantly cycles a display of a gray battery for about ten seconds and then disappears for 6-7 seconds, then the battery re-appears.. After the battery view disappears, the phone has a vibrating "beep". The white circle in the center of the battery is stationary; no rotations. No keystrokes affect the results. After 45 minutes of attempting to charge, there is no change in status. Any suggestions.