My Calculator:
Ti nspire cx cas. Hardware revision D. OS version 3.9.0.463.

What Happened:
So after dropping my calculator and having the buttons act improperly (such as the "8" key acting as the "a" key) my first instinct was to try reloading the OS. While panicking (I hoped I wouldn't have to replace my calculator), in an attempt to fix the buttons, I installed the only OS I had available (stupid me) 3.9.0.463. Which did literally nothing. However I now have the buttons under control (at least enough that I don't feel I need to worry) and would like to return to using ndless. Preferably back to the 3.1 version, as I had zero problems with my calculator before dropping it.

What I've Tried:
So the first thing I tried was to use the downgradefix39 program, but after several attempts using this tutorial I gave up as I was unable to send files after reconnecting (ti software wouldn't recognize it as an attached calculator), failing between steps five and six. Then I saw someone say that on hardware pre-J, you should just use nLaunch. And after trying to look into that I realized I had no idea what I was doing, and didn't want to ruin my calculator.

The question:
Is there a way for me to downgrade from 3.9 with only a usb connection to my computer?