Apple has acknowledged problems with unresponsive iPad Pros in a support document, and the company said it was investigating the issue. The same document provided steps for recovering from the problem.
iPad Pro
The problem first cropped up on Apple's support forums, as noted by Re/code, where user darkfire.shadows said his "iPad Pro shuts off while charging." Many other users chimed in with the same problem, describing incidents where their iPad Pro was unresponsive after being plugged in to charge.
The solution, as noted by Apple in that support document, is to do force restart by "pressing and holding both the Sleep/Wake and Home buttons for at least ten seconds, until you see the Apple logo."
That support doc in full:
Learn what to do if your iPad Pro doesn't respond when you press buttons or tap on the screen, and the screen is black.
To get back to using your iPad Pro, force restart it by pressing and holding both the Sleep/Wake and Home buttons for at least ten seconds, until you see the Apple logo.
Apple is aware of this issue and is investigating.
This document will be updated as more information becomes available.
We'd like to hear from readers who have experienced this problem.