Update:
I'm not sure what happened but "suddenly" the HP EliteDesk started allowing me boot from DVD. However I was getting an error that was crashing the computer. According to HP's website you are to reset everything to factory settings and then re-install ... it's 1:34 am and I don't remember what it said but the end result is that I did what it said and now the computer can't see USB ports OR the DVD drive AND I don't have access to a network port because my wife and I are having work done on our house and the rB&B we are staying in only has wifi with the router in the house next door that the owners are living in and I don't feel comfortable going over there to ask permission to ask to access their network ports.
After delays (totally expected) they are now finally supposed to be with our house in a week and then my wife wants to hire a company to go in and clean up all the dust in the house from the construction. Once that is done we will be back in the house and I will have access to a network port and will be able to have access to a network port.
Firmware. That's what I need to re-download so it can see the USB ports and the CD/DVD drive. Until then it can't so that is what I'm waiting for. I will update you once I know more.
You said that audio wasn't working until you contacted Arca Noae. Care to share what they helped you with, if you remember?