Solved it myself. Posting here for other (newbies') benefit. After installing the drivers, unplug the Duet board and restart the computer. Plug it back in and then connect. Worked for me then.
Now to solve all the other issues I've since encountered.
Hi, I'm completely new to Duet 3d, so this may be a very stupid issue with an obvious solution, but I simply can't find the answer anywhere.
I have a duet 3 mini 5+ WiFi. I installed it in my printer (custom built machine) and wired everything up. I have not yet powered it on using external DC power, only through USB. I am following the getting connected guide: https://docs.duet3d.com/en/How_to_guides/Getting_connected/Getting_connected_to_your_Duet
I have physically connected to the board via USB. The 5" panel due comes on with a red banner on top showing "Connecting" and lots of zeros in all of the fields.
I have downloaded the Duet3d windows drivers, identified the board in the device manager under ports (It's COM3 for me) and installed the drivers. It shows now as a duet 3d device.
I have installed YAT and run it. I have set the settings as per the instructions (Selected COM 3, using the default 9600 bits/second rate) and edited the Text settings to use line feed (LF) as the end-of-line character.
When clicking the green check, I see "Serial Port COM3 - Duet 3 motion control electronics (9600, 8, None, 1, None) is open and connected" and figured this was a good sign.
When trying to view the firmware version (typing M115 in the "Send Text" field and hitting enter) I receive yellow text in the monitor saying "[Warning: 5 bytes not sent anymore.]" which is less than helpful. The board also seems to briefly disconnect and reconnect (The text at the bottom briefly changes to "Serial Port COM3 - Duet 3 motion control electronics (9600, 8, None, 1, None) is closed and waiting for reconnect" and then changes back to the "open and connected" text from before.
Needless to say, I am very frustrated. There is nothing in the guide saying what to do should something like this occur. I have tried connecting through pronterface, but it hangs up.
Any assistance would be much appreciated. Was I supposed to put something on the MicoSD card first before trying to connect? If so, what? There appears to be no indication of pre-requisite steps.
Thanks in advance for any help
EDIT: For what it's worth, I can touch "Setup" on the panel due and see "Panel Due firmware version 1.24". I think that's only the panel's firmware, and not the board's. It also shows 57600 baud. I assume this is the baud rate between the board and the panel. I tried the 57600 rate in YAT just to see and had no luck. For all I know, the board and the panel aren't even talking to each other beyond simply supplying power.