That's what I did to get me into trouble. After downloading and installing the latest firmware 11.313.02.00.01, my SIM was locked and I could not use the modem anymore. I am now using a borrowed modem to search for solution. Hope this procedure will get me back on my feet.
Great post - very well written and easy to follow. Shame the instructions are for Windows, most serious hackers tend to use Linux these days. However, I do have a dual boot machine for such purposes, so all is not lost - Keep up the good work.