I updated to the 3.6.0.546 version in my TI nspire CX, so that's my current OS. I want to put a CAS OS in my calculator. Can someone explain me with details (step by step) how can I do it? And, if it is possible to put a CAS OS, can I put the non CAS OS (my current one) back in the calculator if I want to? How? Please answer quickly, it is very urgent. Thank you