I'm stuck with a useless calculator atm as I deleted the OS wondering if that was causing problems and that didn't help.  Every OS file I downloaded says corrupted OS please download fromthe ti education website.  It was on 1.6 and ti support said I cannot go directly to 3.1 I've tried the student CAS software and nspire computer link.  Is there anything I can do?  I've done much googling to no avail.