My TI Nspire CX says it's current version is at 3.2.0.1219. I want to get downgrade to 3.1 so I can install Ndless. I have wiped to whole calculator and downloaded the 3.1 file, well at least what is labeled as 3.1. When send it to the calculator to install the OS it installs but once it installs it says my version is still 3.2.0.1219. What do I do? Please help!