For the vast majority of JioFi models (JioFi 2, 3, 4, 5, and 6), the default universal credentials are standard and easy to remember.
If your JioFi is frozen and codes aren't working, use the physical master reset button. This works 100% of the time and requires no software.
However, a common search term often trends among tech enthusiasts and frustrated users alike:
Entering incorrect "hard codes" into the device’s internal terminal can permanently disable the router.