buttons froze on iPhone 11, couldn't turn off

I couldn't operate any of the virtual buttons or open any app. When I pressed the physical buttons on both sides, the three sliding buttons appeared, but none of them worked. In the past when I had the same problem, I pressed the physical buttons on both sides again, and then the phone powered off. This time that didn't work. instead what happ[ened is the red sliding button for emergency SOS started counting down from 5. Before it reached 0, I released the two side buttons and the countdown stopped. I wasn't exactly sure what would happened if it reached zero. I couldn't think of anything else to do so I did it again and let it reach 0. It started calling 911 and I was unable to abort. It also contacted my emergency contacts. As I hiked I could see people calling me but I was unable to answer. I was able to drag down from the top and get to the screen with airplane mode, WIFI, cell data, and flashlight icons. The airplane mode and WIFI icons worked, but not the flashlight. Eventually the battery ran down and after I recharged the phone and restarted it, it worked. I wonder if there was an easier way to restart it.