There is no access to ROCK. As an alternative, you can boot a “thumbdrive” distribution (for example an ubuntu install image will do fine) to temporarily boot into an accessible Linux for the firmware update.
I have not tried this, but on my NUC there is a firmware update procedure that uses a firmware image on a thumb drive and a special boot sequence. I don’t remember the details but I believe it does not require you to boot into any OS.
Regarding firmware for an SSD, you probably would need to boot an OS… I’ve not heard of anyone upgrading firmware on an SSD…