I charge my iPhone every night on the nightstand next to my bed using the Material Dock by Studio Neat using an Apple cable and an Apple charger. Recently, I woke up and reached for my iPhone XS only to discover that the screen was completely black and would not come on when I touched the screen or pressed any of the side buttons. At first, I thought that perhaps the battery was completely dead — which would be odd because it had been on a charger all night — but even after I plugged the iPhone in to a different charger, it did not come back to life.
That led me to believe that that iPhone had crashed and needed to be restarted. It has been many years since this last happened to me, and at the time I was using an iPhone with a home button. To restart an iPhone 6s or earlier, you hold down the Home button and the sleep/wake button for a long time until the iPhone restarts. But what do you do on an iPhone, an iPhone XS, or a new iPad Pro which doesn't have a home button?
Apple provides the answer on this support page, and it is nothing that I would have guessed. If you are using an iPhone 8 or later, you press and quickly release the Volume Up button, then you press and quickly release the Volume Down button, and then you press and hold the Side button on the iPhone (or the Power button on the iPad Pro) until the device restarts. The first time I tried this with my iPhone XS, nothing happened. But the second time I tried this strange combination, it worked and my iPhone restarted. And sure enough, upon restart I saw that it was fully charged – so this was some sort of a crash, not a dead battery.
As that support page also notes, if you are using an iPhone 7 or an iPhone 7 Plus, the solution is to press and hold both the Volume Down button and the Side button until you see the Apple logo indicating that the device is restarting.
When you use this method to restart your iPhone, you shouldn't lose any data. You are just forcing the iPhone to shut down and then start up again.
Hopefully it will be a long time before I need to do something like this again, but at least I now know what to do. And so do you.