Turning Iphone On. To turn your device back on, press and hold the side button (on the right side of your iphone) until you see the apple logo. Master your iphone in one minute a day:
Charge the device and then try to turn it on. Release the side button when the apple logo appears, and give your phone about 30 seconds to reboot. On your iphone 6s and earlier, including iphone se (1st generation) press and hold both the home button and the side button or the top button until you see the apple logo.
How to fix iPhone not turning on, stuck at boot loop YouTube
If the phone is off, it should turn on. If it's on, you may see the slider offering to turn it off. Your iphone is designed to turn back on when you connect it to a power source, even when it has no battery life left. Drag the slider, then wait 30 seconds for your device to turn off.