Usb type to reflash pureboot?

[code9n]

Hi, I want to reflash the latest pureboot (20) onto a mini V2 (with Qubes os).
Can I use a mass storage SATA usb device with multiple files on it including the pureboot .rom?
I mean will Pureboot give me the option to choose from the many files on the drive or does it need to be the only file on a usb memory stick to work?
Thanks,

[fsflover]

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