How to power on the iPhone 16 pro

plug it in to charge for 15 minutes. Then hold the SIDE button (on the right side of the phone until an Apple logo appears. It should take about 15 seconds, but hold for up to 30 seconds.

If nothing happens:

• Press and quickly release VOLUME UP

     then

• Press and quickly release VOLUME DOWN

     then

• Hold the SIDE button until an Apple logo appears (15-30 seconds), ignoring "slide to power off" if it appears

The operative word here is QUICKLY; and try it a couple of times, the timing is a little tricky. If done correctly this will always work unless the phone has a hardware problem.