You cannot perform the firmware update using CFast 2.0 cards. Please use a commercially available SD/SDHC/SDXC memory card that is 64MB or more for the firmware update.
Firmware Version 18.104.22.168 is for XC15 camcorders with Firmware Version 22.214.171.124. If your camcorder’s firmware is already Version 126.96.36.199, it is not necessary to update the firmware. Once the camcorder is updated to the latest version, it cannot be restored to a previous version.
For further information, please refer to the latest version of the unit’s Instruction Manual that is released with the firmware update.