This article explains how to use a bootable USB stick to upgrade firmware on a dell server. In this example I am upgrading the BIOS but this procedure will also work for other updates.
From the Dell website enter the service tag of your server and download the dos executable version of the BIOS upgrade
On a Pc running windows plug in your USB stick. Then download and run the following
Select install to a USB flash drive
Copy the BIOS update onto the USB KEY and rename the file to bios.exe
Plug the USB drive into the server and boot up. Press F11 to enter boot menu
Then select the USB drive
Enter “4”, “c:” then “bios.exe”
Once complete remove the USB key and reboot. Job done.