03:00.0 RAID bus controller: Broadcom / LSI MegaRAID SAS 2208 [Thunderbolt] (rev 05)
This is risky but if you have an extra RAID/SAS card to replace it then you can try this to get IT mode.
https://docs.broadcom.com/docs-and-downloads/host-bus-adapters/host-bus-adapters-common-files/sas_sata_6g_p14/9207_8e_Package_P14_IT_Firmware_BIOS_for_MSDOS_Windows.zip
https://docs.broadcom.com/docs/12350477
Get the sas2flash for Linux:
https://doc........
Usually when I come across a system like this, Ijust flash the firmware to an IT mode so we get just an AHCI system with JBOD, but sometimes it is not practical for remote systems or if we fear that flashing is too risky if something goes wrong.
In this case, we unfortunately have to use LSI/Broadcom proprietary CLI tools (megacli) to even make the drives visible.
Step 1 - Download MegaCLI
The official broadcom packages lack .deb packages and only have .rpm for........
1.) Flash directly to this file:
http://tomato.groov.pl/download/K26RT-N/build5x-132-EN/Linksys%20E-series/tomato-E2500-NVRAM60K-1.28.RT-N5x-MIPSR2-132-Max.zip
*I was never able to get the larger "Mega" file to work, at least not initially so I recommend the file above.
To enable 5ghz I had to do the "Clear NVRAM" Option before it was shown.
2.) Or if you don't need 5ghz (most devices do not support it and cannot........