I had upgraded the BIOS and BMC to c220 m4 version SNS3515 -> c220M4 (BIOS & BMC v2.0.x) to disable the secure boot. but the option come back after upgrade the bios & BMC to v4.1.x. Hence I need to fallback it to v2 to disable the secure boot. Now I am facing the problem is the downgrade can only be lowest v 3.0.4m. I try to downgrade lower version, It prompts image "Update aborted. Incompatible image"

Now is
-secure boot enabled -> cannot use c220 m4 HUU iso. invalid signature while boot up the iso.
-GUI and CLI -> prompts "Update aborted. Incompatible image". Even using lower version of SNS-3515 BIOS and BMC firmware also prompts "Update aborted. Incompatible image"
any idea on downgrade to lower version