Troubleshooting Tip: Firewall bricked during the upgrade

[Mrinmoy]

Description	This article describes the issue when the firewall is not coming up while upgrading the firmware. This problem may happen if the upgrade path is not followed properly or any unwanted interruption during the upgrade process. Let's consider a firewall 40F is running on 6.4.10 and the target firmware is 7.4.4. If checking in the upgrade path tool (Upgrade Tool), the path is: Now if someone jumps directly from 6.4.10 to 7.4.4 skipping the other version, the firewall may not come up properly.
Scope	FortiGate 6.4 or above.
Solution	In such a case, the following step should be performed: Access the firewall physically via a console connection. Technical Tip: How to connect to the FortiGate console port Using putty check the status of the firewall. Reboot the firewall and it will give the option 'press any key to display configuration menu'. FortiGate-40F (03:00-06.02.2023) Ver:05000100 Serial number: FGT40FTKXXXXXXXX CPU: 1200MHz Total RAM: 2 GB Initializing boot device... Initializing MAC... NP6XLITE#0 Please wait for OS to boot, or press any key to display configuration menu. [C]: Configure TFTP parameters. [R]: Review TFTP parameters. [T]: Initiate TFTP firmware transfer. [F]: Format boot device. [I]: System information. [B]: Boot with backup firmware and set as default. [Q]: Quit menu and continue to boot. [H]: Display this list of options. To load the default firmware. After selecting option ‘B’ the firewall will take a few minutes to show up on the login screen. Enter C,R,T,F,I,B,Q,or H: Loading backup firmware from boot device... Booting OS... .Initializing firewall... System is starting... Starting system maintenance... Scanning /dev/mmcblk0p2... (100%) Scanning /dev/mmcblk0p3... (100%) FortiGate-40F login: Using the last known user ID and password login to the firewall. The firewall GUI access will be available at that time. If that step does not work, then the only option left is to format the device and reload the image. But in that case, all config will be wiped. It is necessary to reconfigure the firewall or reload the previous backup config file. Technical Tip: Formatting and loading FortiGate firmware image using TFTP