Just to let others know, I was having the same problem as the OP. I had to force the update of the firmware using the instructions linked above using the BOSSA method and a connected Pi 4. Once that was done the board was connected and the web UI showed the tools and axes in the dashboard.
Thanks everyone.

@stuartofmt
Great, thanks for the reply. I might wait for the release since I had some weirdness when I tried 3.6.0 rc2. I was messing with several things at the time so maybe it was unrelated. In the meantime I have been manually checking my config into github.

Thanks again and I look forward to trying this out.

Pi OS:

lsb_release -a
No LSB modules are available.
Distributor ID:	Debian
Description:	Debian GNU/Linux 12 (bookworm)
Release:	12
Codename:	bookworm

@stuartofmt Thanks for the reply.

I am using a pi 4 as my SBC. My board is Duet 3 MB6HC. I am running the standard distribution version 3.5.4.

pip list
Package             Version
------------------- -----------
attrs               22.2.0
av                  12.3.0
certifi             2022.9.24
chardet             5.1.0
charset-normalizer  3.0.1
colorzero           2.0
dbus-python         1.3.2
distro              1.8.0
distro-info         1.5+deb12u1
gpiozero            2.0.1
idna                3.3
jsonpointer         2.3
jsonschema          4.10.3
lgpio               0.2.2.0
libarchive-c        2.9
numpy               1.24.2
olefile             0.46
pidng               4.0.9
piexif              1.1.3
pigpio              1.78
Pillow              9.4.0
pip                 23.0.1
pycryptodomex       3.11.0
PyGObject           3.42.2
PyOpenGL            3.1.6
PyQt5               5.15.9
PyQt5-sip           12.11.1
pyrsistent          0.18.1
python-apt          2.6.0
python-prctl        1.8.1
requests            2.28.1
rfc3987             1.3.8
rpi-lgpio           0.6
setuptools          66.1.1
simplejpeg          1.8.1
six                 1.16.0
smbus2              0.4.2
spidev              3.5
ssh-import-id       5.10
toml                0.10.2
tqdm                4.64.1
unattended-upgrades 0.1
uritemplate         4.1.1
urllib3             1.26.12
v4l2-python3        0.3.5
webcolors           1.11.1
wheel               0.38.4

sudo find / -name cv2

Yields nothing.

Thanks in advance for any insight.

@stuartofmt
This is great, thanks. But right now when I try to install the plugin I get the error:
"Failed to install package opencv-python, package manager exited with code 67"
Any guidance?

Duet 3 MB6HC MB6HC 3.5.4
Duet 3 Expansion TOOL1RR TOOL1RR 3.5.4
Duet Software Framework DSF 3.5.4
Duet Web Control DWC 3.5.4

Thanks

Just to let others know, I was having the same problem as the OP. I had to force the update of the firmware using the instructions linked above using the BOSSA method and a connected Pi 4. Once that was done the board was connected and the web UI showed the tools and axes in the dashboard.
Thanks everyone.