Hello

Check the boot order and try a different file system, FAT32 works best for USB. Also, the boot mode may not be supported by whatever you have installed on the USB, try switching between BIOS and UEFI.

http://www.dell.com/support/

Thanks

Im in the same boat....

Cannot boot from the Bootable USB that was made with Rufus and the latest Dell ISO for the R630 Packages.

The BIOS/Lifcycles can see the USB stick.

Cannot set the boot order to a USB option, there is no USB option in Boot menu.

There is a DVD Optical drive.... thats funny!

The only way thats worked is load int Lifcycles and select Firmware update - then point to the BIOSupdate.exe and the Lifecycles.exe.

They cant be in a folder, need to be in root.... sigh.

Cant point it to the Repository folder that the Dell IOS Package has with all the firmware... sigh.

Tried multiple USB ports, tried multiple Bootable USB sticks.

This is an air gaped system. Cannot use online updates and should not be forced to.

Really disappointing that something that should be so simple is so limited.

I would suggest since this is a one time boot, press F11 at bootup to enter the Boot Manager, then select One-Shot BIOS Boot Menu>  then you should see your USB key in the list. Click it with your mouse and it should boot to the USB key. Here is a shot of the key seen in the F11 boot menu, and below that are some screenshots of the BIOS screen and how to change the boot order from there.  If the system still doesnt boot from the USB key, either something is wrong with the key or the iso download was corrupted to 

After pressing F2 to enter the BIOS, select Boot Settings>BIOS Boot Settings> then scroll down to Hard-Disk Drive Sequence, and you can change the order there. I have bios 2.8.0 and idrac 2.63..60.61 and it lets me change the sequence in the Boot Sequence field in the first screenshot below. 

#Iwork4Dell