Hi Bluegrasser -
See if you can purchase a copy of BMW Scanner 1.4 (or PA Soft 1.4). Maybe someone local to you has a copy. I have a copy from days when I owned an E46 325xi, but I'm in Minnesota. It will clear Transport Mode and does diagnostics on many/most of my E86's modules. I does not code much, and it may not communicate with every module, but it will do the Transport Mode, diagnose, and it will find your factory blue tooth code. I'm afraid I'm not of much help in advising source to purchase or best device to host it - I run mine on an aged WindowsXP laptop.
Search for "BMW Scanner 1.4 Transport Mode" or view Colb's post here: https://z4-forum.com/forum/viewtopic.php?t=134662