Thanks, that is exactly what I did, after panicking. I guess everybody has a first time for thinking they've killed their phone.
(I thought I had turned it off but I guess my fumble-fingers somehow restarted it because I came back after awhile to discover it had been trying to activate -- I'm using it wifi-only -- and I stupidly tried to turn it off. Which locked it up with a blank screen but the buttons all still lit up and nothing I did changed this. After calming down, I was trying to pull the back off when it popped back to life, but it wouldn't find my router. But pulling the battery seems to have done the trick.) And I redacted my comment out of embarrassment.
Yeah, I'm new to smartphones.