Q: Software update 9.3.3

Your phone has gone into recovery mode and must be restored. Take a look at the instructions here.

If you can't update or restore your iPhone, iPad, or iPod touch - Apple Support

Apple suggests these steps

Update your device using iTunes

If you can’t update wirelessly, you can update with iTunes. If your computer uses the Personal Hotspot on the iOS device that you’re updating, connect your computer to a different network.

1. Install the latest version of iTunes on your computer.
2. Connect your device to your computer.
3. Open iTunes and select your device.
4. Click Summary, then click Check for Update.
   
5. Click Download and Update.

See more information here Update the iOS software on your iPhone, iPad, or iPod touch - Apple Support