Can I update the SSD firmware from a bootable USB flash drive?
If you are using a PC, yes.
The firmware update can be run from a bootable USB flash drive, providing the SSD is connected via SATA directly, provided the computer can boot from a USB flash drive. The Firmware update guide has step by step instructions on how to update the firmware using a USB drive, and can be downloaded from the firmware update page.
At this time we do not have a USB process to update the firmware on Mac systems.