Here's some added tips:
1. The thumb drive you use for Replicated Setup would ideally be only used for that, and have nothing else on it. Once you find one that works for you keep it labeled for that purpose. I'm sure some of the newer thumb drives have features present that can keep them from being identified by the primative operating system that BIOS actually is.
2. The CPQSETUP.TXT files are tiny.... the thumb drive can be a very low capacity one, and maybe that would be best to use versus a bigger one.
3. I'd do a low level format (a USB thumb drive low level wipe) on that small old junker thumb drive first..... I use the little utility from HERE and have been using that for years.
http://www.roadkil.net/program.php/P14/Disk%20Wipe
Please note that some thumb drives have had non-standard things done to them by the manufacturer, deep inside their sectors, so hunt around in your desk for old small ones and try a few before giving up. I remember that SanDisk put out a limited number of USB drives that had some troubles due to a misunderstanding about W8 requirements. Old and low capacity is what you are looking for here.....
4. I format that thumb drive after the low level wipe using FAT32 format type.
5. You obviously would not want to use a thumb drive that is write protected.
6. In BIOS you can turn off the option to boot from a USB drive, and that may help prevent BIOS confusion.... just go to the boot order area of BIOS and highlight USB in the list, and use F5 to gray it out, and don't forget to F10 save as you exit that area and also choose to save your changes and F10 to confirm.
7. There is advice to always have that thumb drive in place before you push the start button (that is a "cold boot"), but as noted in the first post above I also have been able to use Replicated Setup from a restart.
8. BIOS is generally too primative to have USB3 drivers..... so don't try Replicated Setup from the blue USB3 ports on the front/back. Always find a black USB2 port instead. Try a rear USB2 port if you're not getting success with one of the front USB2 ports. I habitually have used the top front port, and that is USB2 for the Z620 while the lower blue ones are USB3.
9. I have run into rare cases where I could get control of BIOS only by using a PS2 keyboard and not by using a USB keyboard. Thus, when I am building up workstations I always use PS2 keyboard and mouse. I'd say the PS2 mouse is less important for these rare cases than the PS2 keyboard. You can get nice HP PS2 keyboards and mice off eBay, new, cheap. It is worth a try......
For what it is worth I have never, ever, not been able to use Replicated Setup via a USB stick on any HP workstation. I think it basically is a matter of finding the right thumb drive that can be recognized by BIOS, but the tips above can help. And, there is info in that first post above that is not here, so read and understand both.