I should have asked this earlier, did you run the installer for the on off shim?
yes, I ran the one line installer.
plus sudo chmod +x /lib/systemd/system-shutdown/gpio-poweroff
Power supply plugged into the On Off shim? It looks like you may have it plugged into the Pi?
The software installer should install and setup the power off signal from the Pi to the on off shim. You don’t want to that “and” the dtoverlays.
the power is plugged into the shim. dtoverlays (as described above) are removed.
the button will trigger a shut down, but I have to unplug power to kill the pi’s red LED after button-initiated shutdown.
when I plug power back in soon thereafter, the pi will boot right away.
but when I wait about a minute or longer to plug power back into the shim, the pi will not reboot unless I hold the button for a little while.
so apparently the button CAN boot the pi and really the only thing that’s missing from an end-to-end success is the power cut after shutdown.
Do a shutdown, wait a while, then ground GPIO 4. If the Red LED on the Pi doesn’t go out its a fault on the On Off shim. If it does go out, then the Pi isn’t pulling that pin low for some reason.
well … this is embarassing.
I did as you said, connecting GPIO4 to GND didn’t cut power.
then I took a good hard look at the shim. Long story short: after reworking the soldering of Pin4 to the header the entire assembly works exactly as it should.
thanks for your consistent support and patience and pointing me in the right direction.
Stuff happens. You figured it out, now you can get to tinkering with the rest of it. =)