AirPrint can be accessed in the browser Safari, Mail, Camera, Photo, Maps and many other applications.
To send an item for printing, click the application icon
and then click “Print” or the printer icon.
In order for the AirPrint function to work, it is necessary to be in the same Wi-Fi network with a printer that supports AirPrint or a computer with special software installed and a printer connected to it.
To turn on the iPhone without a power button, just connect it with a USB cable to your computer.
If the iPhone does not turn on immediately, the battery is likely to be completely depleted, in which case it will be necessary to wait about 10 minutes until it has enough charge to turn on, after which the iPhone will turn on.