1. Connect to the firewall via the Console port using a console cable, with the following parameter.
Baud 9600
Data Bits: 8
Stop Bits: 1
Parity: None
Flow Control: Off
3. You should be able to see the firewall CLI login screen.
4. Reboot your device and wait until the boot process is complete.
5. Type in the username: maintainer and password is the combination of the word bcpb + serial number of the firewall (remember all serial number charachters in capital letters).
Example: bcpbFGT60B7612104239 (NO, it’s not the real S/N)
Note: you will have only 14 seconds to login as user “maintainer” after the boot process.
So it will be better if you type the password on a text editor and copy and paste it on the terminal console.
6. Now you have full access to your Fortinet box, so you can proceed to change the password with the following commands:
config system admin
edit admin
set password
set accprofile super_admin
end
This above method worked on my Fortigate 60B and hope the same will work on other models also.