It could be in the bios or have a separate bios for the RAID system. Sometimes you will see it flash on screen as it boots. Like: F6 for RAID configuration

Not sure if using a network device with no security updates and a firmware that might be found online is worth it. Also, I would never flash a networking device with a firmware that is found on a random website. After all that, most of the features of Cisco devices are still locked behind a license key.

Unfortunately most of the features of their devices are only available through their licensing. Also you won’t be able to get updates to it without a support contract. Even if new it generally isn’t worth using at home.