BTW, I tried Private Sub NewWOBtn_Click()

    DoCmd.OpenForm "WODetailF", , , , acFormAdd, acDialog, Me.DeviceID

    
End Sub

and now it does nothing.

If the field is available on the current Form you can set a Default Value
If the field is NOT available on the current Form you can use DLookup

I neither fit your needs, please post some screenshots.

Since your WODetailF is being opened as a Dialog, all other scripts stop until that form closes, so you'd have to handle setting your fields in that form.

Possibly something as simple as in the "OnOpen" event setting the defaults with the DLookup as Kevin pointed out or using a recordset to get the data.

You've sent the DeviceID as an OpenArg, so somewhere in that form, you'll need to set DeviceID = OpenArgs. Sending the OpenArgs value itself doesn't do anything unless you have script on that form to read and process it. The Custom MsgBox series explains how OpenArgs work.

When I click the Work Order button on DeviceF, everything with blue lines populates, all defaulting from the device id through wodetailq. If I click the New Work Order button on this form, it wants to make a new, blank record for a non-existent device. It doesn't even pull the DeviceID

Well, that explains why that code broke everything and it won't even open the form now. Something I found on StackExchange

OK, I got it back to where the New Work Order button will open the blank form again, but it's pulling for a new device, and is also uneditable. The underlying query should be pulling this info in for the open device.

Private Sub NewWOBtn_Click()
    
    DoCmd.OpenForm "WODetailF", , , WODetailID = " & WODetailID"
    
End Sub

Try:

DoCmd.OpenForm "WODetailF",,,"WODetailID=" & WODetailID