my phone shut off unexpectedly, fully charged and refuses to turn back on
Have you tried holding the home and power button at the same time for several seconds?
What to do if your iPhone or iPad will not turn on | Apple Support Communities
it came on!!! thank you! i wonder why it wasn't coming on by just holding the power button?
Could have been a battery malfunction. This happens sometimes, especially near really low/dead battery levels. We see it often here in the community.
