This is really a follow-on to https://github.com/modmypi/PiModules/issues/60 .

System is Pi 3B running Ioannis' image downloaded from Google Drive.
Firmware is `UPS_PIco_HV3.0_main_29_120721_GPIO_USED.hex` as supplied on the above image.
No settings have been changed.

System starts OK and seems to be running: UPS LED is ON, all others are OFF

$ python pico_status.py

********************************
UPS PIco HV3.0A Status
*****************************

UPS PIco Firmware.......: 29
UPS PIco Bootloader.....: 53
UPS PIco PCB Version....: 41
UPS PIco BAT Version....: LiPO (ASCII: S)
UPS PIco BAT Runtime....: 2 MIN
UPS PIco STA Time Left..: 127 SEC
UPS PIco r232 State.....: OFF

Powering Mode...........: RPi POWERED
BAT Percentage..........: 93.3333333333 %
BAT Voltage.............: 4.1 V
RPi Voltage.............: 5.4 V
NTC1 Temperature........: 33 C
TO-92 Temperature.......: 00 C
Extended Voltage........: 14.3 V
A/D2 Voltage............: 0.0 V

PIco FAN Mode...........: AUTOMATIC
PIco FAN State..........: OFF / AUTO
PIco FAN Speed..........: 50 %
Pico FAN Temp Threshhold: 50 C

*****************************
Powered by PiCo
*****************************
$ systemctl status picofssd
● picofssd.service - LSB: PiModules(R) UPS PIco file-safe shutdown daemon
Loaded: loaded (/etc/init.d/picofssd; generated)
Active: active (running) since Mon 2021-09-13 17:29:09 BST; 9min ago
Docs: man:systemd-sysv-generator(8)
Tasks: 2 (limit: 871)
CGroup: /system.slice/picofssd.service
└─776 /usr/bin/python /usr/local/bin/picofssd --log-level debug --pid-file /var/run/picofssd.pid --xml-config /etc/pimodule

Sep 13 17:29:07 raspberrypi systemd[1]: Starting LSB: PiModules(R) UPS PIco file-safe shutdown daemon...
Sep 13 17:29:09 raspberrypi systemd[1]: Started LSB: PiModules(R) UPS PIco file-safe shutdown daemon.
Sep 13 17:29:24 raspberrypi picofssd[776]: <INFO>: Started
Sep 13 17:29:24 raspberrypi picofssd[776]: <DEBUG>: False
Sep 13 17:29:24 raspberrypi picofssd[776]: <DEBUG>: None
Sep 13 17:29:24 raspberrypi picofssd[776]: <DEBUG>: None
Sep 13 17:29:24 raspberrypi picofssd[776]: <DEBUG>: None
Sep 13 17:29:24 raspberrypi picofssd[776]: <DEBUG>: None

However, two things:
If I remove power, I then get:
UPS LED stays ON, and BAT LED stays OFF. And

$ python pico_status.py

*****************************
UPS PIco HV3.0A Status
*****************************

UPS PIco Firmware.......: 29
UPS PIco Bootloader.....: 53
UPS PIco PCB Version....: 41
UPS PIco BAT Version....: LiPO (ASCII: S)
UPS PIco BAT Runtime....: 2 MIN
UPS PIco STA Time Left..: 127 SEC
UPS PIco r232 State.....: OFF

Powering Mode...........: ERROR
BAT Percentage..........: 80.0 %
BAT Voltage.............: 4.0 V
RPi Voltage.............: 5.2 V
NTC1 Temperature........: 32 C
TO-92 Temperature.......: 00 C
Extended Voltage........: 13.9 V
A/D2 Voltage............: 0.0 V

PIco FAN Mode...........: AUTOMATIC
PIco FAN State..........: OFF / AUTO
PIco FAN Speed..........: 50 %
Pico FAN Temp Threshhold: 50 C

*****************************
Powered by PiCo
*****************************

(NB I enabled loglevel=debug)

and, after 5 minutes, the UPS LED goes OFF and stops operating.

$ python pico_status.py

*****************************
UPS PIco HV3.0A Status
********************************

UPS PIco Firmware.......:
Traceback (most recent call last):
File "pico_status.py", line 206, in <module>
print " ","UPS PIco Firmware.......:",fw_version()
File "pico_status.py", line 27, in fw_version
data = i2c.read_byte_data(0x69, 0x26)
IOError: [Errno 121] Remote I/O error

Pressing `IR` causes UPS to restart for another 5 mins.

I have a video, but not sure where to upload it.