...
FlashFig support is enabled on every new RouterBOARD manufactured since March 2010 by default from the factory. For older models, FlashFig can be enabled via RouterBOOT or from MikroTik RouterOS console - /system routerboard settings set boot-device=flash-boot-once-then-nand or /system routerboard settings set boot-device=flash-boot.
After FlashFig is used once mode on a brand new RouterBOARD , it is disabled on further boots only after the first successful user login or successful FlashFig attempt to avoid unwanted reconfiguration at a later time. To use FlashFig a second time on the same router, you need to enable flash-boot in Bootloader settings (this setting will revert to NAND after a successful configuration change OR once any user logs into the board).
...