Question: I want to install ubuntu 14.04 unto a Dell Precision 7810. I created a
USB drive using the "Startup Disk Creator". Installation went
smoothy. Unfortunately, it failed at boot time with "No boot device
found". 

To fix it, I booted off the USB drive and use "Try Ubuntu". When
ubuntu came up, I installed and ran boot-repair. All seem well (output
<http://paste.ubuntu.com/12016810/>). Unfortunately, it still fails with
the same error.

Thanks for your time and consideration.

-jk

Answer: 
I ran into the same issue installing CentOS and RHEL 6.7. It turns out that I needed to use a UEFI compatible USB drive. I used about 4 drives before I found a Kingston DT R3.0 G2 drive that worked. 

On a Windows 7 system I used RUFUS 2.3.709 to create a bootable ISO. I know this sounds far fetched but it's something to do with how the non uefi compatible USB drive present themselves during the install that corrupt or damage the MBR.
Have you solved this problem? I ran into the same problem with our lab's T7810. After several days of scratching my head, I finally found the cause of this problem and the solution. It seems that dell has forced the UEFI to look for a specific file to boot: `\EFI\BOOT\BOOTX64.EFI` . This is a file for the booting of windows OS, so even though the Linux Server system has been installed to the hard drive, the BIOS will still ignore the Ubuntu's booting file, which is located at `\EFI\ubuntu\grubx64.efi` , causing the problem "**No boot device found**". The solution can be simple: install the Ubuntu server under UEFI mode, boot the installer through DVD or USB again, choose "rescue system" or something like that, and run a shell without filesystem. In the command line, mount the hard drive that has been installed with the Ubuntu by "`mount /dev/sda1 /mnt` " (usually it's sda1), and create the required directory by "`mkdir /mnt/EFI/BOOT`", enter the directory " `cd /mnt/EFI/BOOT`", then fake the windows booting file "`cp ../ubuntu/grubx64.efi ./BOOTX64.EFI`" . Then restart the computer, the Ubuntu should be able to boot now.