Fortinet 5003A ユーザーズマニュアル

Use this command to change the firmware image used to start the FortiSwitch-5003A board by 
switching between the primary or secondary firmware image. To use this command you must install a 
primary and a secondary firmware image by using the system startup options available when you 
reboot the FortiSwitch-5003A from a console connection to the FortiSwitch-5003A COM port.

execute bootimage {primary | secondary}