Trying to update BIOS from here:
https://support.hp.com/gb-en/drivers/selfservice/swdetails/hp-pavilion-23-q100-all-in-one-desktop-pc...
The PC existing BIOS is v0.12. It will have windows 10 on it but currently there is a new blank SSD.
I'm using another PC to run the download sp97015.exe, which runs "HP BIOS Update and Recovery" and choosing the option
"Create Recovery USB flash drive"
A fresh format on a (definitely 100% tested and working) 4Gb USB drive,
"The recovery flash drive was created successfully" is the result. It creates a FAT32 file, and the contents are browseable.
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However. It is not a bootable USB. It's not recognised by the q199na either in EFI or Legacy mode. I tried it in other PCs and no, not bootable. This seems like a faulty BIOS update program.