From MikroTik Wiki
This page shows how to upgrade the Bootloader firmware of a RouterBOARD device.
- Run command /system routerboard upgrade
- Reboot your router to apply the upgrade (/system reboot)]
Note! If you need to install a different version than included in your "routerboard.npk - Upload the latest RouterBOOT firmware to your router's FTP, the latest firmware is available on routerboard.com and then follow above steps.
Checking RouterBOOT version
This command shows the current RouterBOOT version of your device, and available upgrade which is either included in routerboard.npk package, or if you uploaded a FWF file corresponding to device model:
[admin@MikroTik] > system routerboard print routerboard: yes model: "750" serial-number: "1FC201DD513B" current-firmware: "2.18" upgrade-firmware: "2.20" [admin@MikroTik] >
In this case you see, that there is a newer version of the Bootloader firmware available already inside your current RouterOS version.
If there is no IP connectivity with your RouterBOARD, you can also use the Serial Console XMODEM transfer to send the FWF file to the router, while connected via Serial Console. From the Bootloader menu it's possible to upgrade the firmware with this method. This method is the last resort, and should be used only if the first two methods are not available.