PocketBeagle on battery input does not shut down completely

[Paul Beam]

I having a problem (again) with PocketBeagle power.  If I power from the battery input with 5V, it does not completely shut down all the power supplies -- Vout=5V, all the 3.3V outputs are 3.3V, etc.  I have installed the latest iot image: bone-debian-10.3-iot-armhf-2020-04-06-4gb.img.xz.  The console log ends with this:

[  OK  ] Stopped File System Check on Root Device.

[  OK  ] Reached target Shutdown.

[  OK  ] Reached target Final Step.

[  OK  ] Started Power-Off.

[  OK  ] Reached target Power-Off.

[   44.807732] systemd-udevd[673]: Process '/bin/chgrp -R gpio '/sys/devices/pla              tform/ocp/ocp:P1_26_pinmux'' terminated by signal TERM.

[   44.829181] systemd-udevd[678]: Process '/bin/chmod -R g=u '/sys/devices/plat              form/ocp/ocp:P1_12_pinmux'' terminated by signal TERM.

[   44.845789] systemd-udevd[671]: Process '/bin/chgrp -R gpio '/sys/devices/pla              tform/ocp/ocp:P1_28_pinmux'' terminated by signal TERM.

[   44.859571] systemd-udevd[676]: Process '/bin/chmod -R g=u '/sys/devices/plat              form/ocp/ocp:P1_29_pinmux'' terminated by signal TERM.

[   44.876916] systemd-udevd[681]: Process '/bin/chmod -R g=u '/sys/devices/plat              form/ocp/ocp:P1_10_pinmux'' terminated by signal TERM.

[   44.889420] systemd-udevd[672]: Process '/bin/chgrp -R gpio '/sys/devices/pla              tform/ocp/ocp:P1_20_pinmux'' terminated by signal TERM.

[   44.911753] systemd-udevd[678]: Failed to wait for spawned command '/bin/chmo              d -R g=u '/sys/devices/platform/ocp/ocp:P1_12_pinmux'': Input/output error

[   44.926193] systemd-udevd[671]: Failed to wait for spawned command '/bin/chgr              p -R gpio '/sys/devices/platform/ocp/ocp:P1_28_pinmux'': Input/output error

[   44.941205] systemd-udevd[673]: Failed to wait for spawned command '/bin/chgr              p -R gpio '/sys/devices/platform/ocp/ocp:P1_26_pinmux'': Input/output error

[   44.955964] systemd-udevd[676]: Failed to wait for spawned command '/bin/chmo              d -R g=u '/sys/devices/platform/ocp/ocp:P1_29_pinmux'': Input/output error

[   44.970423] systemd-udevd[681]: Failed to wait for spawned command '/bin/chmo              d -R g=u '/sys/devices/platform/ocp/ocp:P1_10_pinmux'': Input/output error

[   44.984943] systemd-udevd[672]: Failed to wait for spawned command '/bin/chgr              p -R gpio '/sys/devices/platform/ocp/ocp:P1_20_pinmux'': Input/output error

[   45.211195] reboot: Power down

I'm using the battery input because it is more tolerant of brownouts, but I guess I need to know if this is supported and I can expect to get it to shut down properly before spending a lot of time trying.,  I read mixed things about whether battery power is supported.