Is there anything we can do if, after step 7, step 8's 'enter 'dload'' instruction gives "invalid command : dload"?
Shutter13 made a very good point. Make sure mtty is closed when you run the FrankenKaiser program. I will answer my own question for those who believe they've messed up at step 7:
1. Remove power from your phone
2. Connect power and hold power button until the green light comes on
3. Make sure mtty is CLOSED
4. Run the "FrankenKaiser-V1.9517.exe /dev/com9 SPL1.56-KAIS-unbricker.nb" (with your own comport, etc.). It should show the 10 character code and instruct you to replug the USB.
5. REPLUG THE USB
6. Run mtty and connect to your comport.
7. 'echo_on' should now work. Do step 7 again.