Stored separately from the firmware itself, in the mainboard's EEPROM, you have statistics of your printer, calibration data related to the movement of the printer, and PID values for heating. If these values become corrupted or are not compatible with a new version of the firmware, you can have some issues. If so, we recommend doing a factory reset to clear these values.
If you are seeing any inconsistent behavior we recommend also flashing the firmware. A factory reset followed by flashing the firmware and recalibrating will resolve most firmware issues you may encounter.