What's the full version string ?
The latest version I know of is 4.0.1.43 :

But if you have a Boot1 version 4.0.1 or newer, then nBoot+ControlX can't work on your calculator.
It doesn't mean you can't run Linux, but you won't be able to put it as a boot image.
You can hot-run Linux from the TI-Nspire OS with Ndless.
See https://tiplanet.org/nspire_linux_builds/
But I don't think those images were never updated for the new 240x320 TI-Nspire CX screen introduced with Boot1 4.0.1.