my iphone turns off and when turn it back on, it tells me that needs to be connect it to power oulet it shows that it doesnt have battery and my iphone only works when its connect to power oulet
Take it to Apple for evaluation and possible replacement.
Mine is the same way. 7.1 didn't fix it. Sometimes turns off above 60% and requires power to turn on and stay on. Once power is connected and it turns on, it operates as normal and the power is back to whatever it was before it shutdown.
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