Q: After IOS upgrade my phone is not starting

Reset the phone: press both the home and lock buttons for up to 1 minute, releasing when the Apple logo appears.

Force your device to start. To do this, press Sleep/Wake and Home buttons and hold them for at least 10 seconds.

Try to reset your device. This won't delete your data stored on the phone.

• Press and hold the Sleep/Wake button
• Press and hold on the Home button
• Keep holding both buttons until the display turns off and back on with Apple logo on it.

If this does not help, take a look these Apple Support articles:

If your iPhone, iPad, or iPod touch doesn't respond or doesn't turn on - Apple Support

Use iTunes to restore your iPhone, iPad, or iPod to factory settings - Apple Support.

If nothing works, I'd place the phone in Recovery mode, then restore it from a backup made by iTunes.

To enter Recovery mode:

1. Turn off your device and leave it off.
2. Plug in your device's USB cable to a computer with iTunes.
3. Hold down the Home button on your device as you connect the USB cable. ...
4. When you see the iTunes logo and USB cable screen, release the Home button.