Your course of action depends on whether your calculator came with 5.4 or you updated to it .
Texas Instruments (TI) uses a "minimum version" lock in the calculator's hardware (NAND Flash). This prevents users from reverting to an older, supported OS like 5.3 once 5.4 has been installed. Current Compatibility: ndless for 5.4
Ndless acts as a "jailbreak" for TI-Nspire calculators, removing the restrictions imposed by the factory firmware. Key features include: Your course of action depends on whether your