The Centipede is programmed to power down automatically unless the power button is held for at least 10 seconds. If you stop holding it down just because the green LED is showing, that is not long enough.
No, this was much later, when the Centipede would normally become available and the indicator would switch to flashing red/yellow.
I finally did find the fix. Apparently I had downloaded firmware updates but never installed them. I haven’t encountered the problem since updating all boards.