Technical Note: How to restore a FortiManager unit operation, following an RMA hardware replacement

Please note:
The FortiManager backup configuration must ONLY be restored on a system with a factory default configuration, and running the same firmware version, as the previously used system.

Steps:

1. Use the following two commands, in this particular order, to reset a FortiManager unit to the factory default configuration:

exe reset all
exe format disk

2. Restore the backup configuration file.

3. Once the configuration backup file has been restored, "Offline Mode" must be disabled:

conf fmsystem/system admin setting
set offline_mode disable
end

4. Since the FortiManager serial number has changed, it no longer matches what is configured in the "central-management" configuration section of all managed FortiGate units, and therefore, FGFM management tunnels will not establish.  The following FortiManager CLI command will re-authenticate the connections to each FortiGate, and will overwrite the old FortiManager serial number with the new one:

exe fgfm reclaim-dev-tunnel