[CentOS] Help with an HP Proliant gen10 plus?

Just starting and trying to boot off the SPP firmware update ISO image on a USB stick.

I made the stick with:

# mkfs.vfat /dev/sdb # dd bs=4M if=P52581_001_gen10spp-2022.09.01.00-SPP2022090100.2022_0930.1.iso of=/dev/sdb status=progress

The usb drive is 16GB and the iso is 9GB.

seem to boot from it and go into auto install of firmware then died with

starting initrd...

warning!!! Unable to mount the file system [cdrom] warning!!! Unable to mount the file system

Preboot maintence mode

/bin/ash: can't access tty: job control turned off

and at # prompt.

There is no cdrom on the gen10 plus.  Only in internal bootable usb port.