Aporte original por: Sunny ,
Your power flex is most likely water damaged so when you hold it down, it is not making a solid connecting. the best way to test this out is to turn on assistive touch, and hold on to the capacitive power button. if it is able to turn off, then is it the button issue. if it is not then, try to restore the phone in DFU mode. hope that helps, if it does please choose my answer. good luck!