VRTX - Updating NICs firmware

I might be missing something obvious, but I can't figure out how to update the firmware of the chassis-attached NICs on a VRTX.

Mapping a NIC to a blade and trying to update its firmware from the blade's iDRAC doesn't work (it does put a job in the queue, reboot the server and go as far as the update screen, but then fail).

And there's no "update" tab on the CMC interface for PCIe components (there is one for the storage components, so I was kind of expecting something similar...).

Any idea?

NICs are Intel I350-T4. Current firmware is 15.0.27. Target firmware is 16.0.24. Everything else on blades and VRTX chassis is latest version, AFAIK. This is an Express CMC license.