The diagnostic files have changed in the new models of SSL Visibility Appliances, the SV-S550. Data that was once available in certain files is no longer available. This requires you to search for data in other places. The BIOS version is one of them.
The BIOS version can be found in the /var/log/kern file.
Jun 01 19:19:30 localhost kernel: DMI: Symantec Miami/Miami, BIOS 0ACNU422 02/08/2023
The platform can be found in the user_syslog.txt file.
Jun 01 14:30:24 sslv_5_4_1_x-7-x86_64.localdomain ssldata[22493]: [N] Detected platform : SV-S550