You have a pretty outdated BIOS so id recommend updating that.

https://www.dell.com/support/home/en-us/drivers/driversdetails?driverid=jy3c7&oscode=wlh&productcode=latitude-e6220

Did you properly reformat the USB drive for the Ubuntu Install that is going to be booted from?

And did you reset your BIOS to its default settings and update it so you can get secure boot enabled?

I have not updated the Bios but I will do this. The Important information section of the latest Bios for the E6220 which is A14 https://www.dell.com/support/home/en-us/drivers/driversdetails?driverid=jy3c7&oscode=wlh&productcode=latitude-e6220

states: 

If BIOS version A01 or any earlier version is currently installed on your system, you must first update to BIOS version A02 before installing the latest update.
A02 BIOS link: : https://www.dell.com/support/home/us/en/04/drivers/driversdetails?driverid=9207V

- If BIOS version A03 is currently installed on your system, you must first update to BIOS version A04 before installing the latest update.
A04 BIOS link: https://www.dell.com/support/home/us/en/04/drivers/driversdetails?driverid=64F9R

This seems to suggest it is OK to upgrade from A02 and A04 to A14 but not from A01 and A03, is this correct? Can I juts upgrade directly from A02 to A14?

The Ubuntu USB drive seems to of been formatted correctly, I formatted it as FAT32 as I have done in the past. I used Rufus in windows and Ubuntu start disk creator and neither method work. I have not read anything that seems to indicate doing anything special?

It’s fine if you upgrade from A02 to A14.

I have manged to get a Unbuntu USB drive to boot. The steps I carried out were:

I updated the Bios to A14 without issue, applied the default settings in the Bios

I used Rufus in Windows 10 to create the Ubuntu USB drive. I used GPT and UEFI - this failed to work but I got a Bio error message saying there was no bootable USB.

I then search Ubutnu forums and found this discussion:

https://ubuntuforums.org/showthread.php?t=2299040

When I ran the script below on my Ubuntu PC with the USB drive inserted:

sudo parted -s /dev/sdd print

 The output looked like this

$ sudo parted -s /dev/sdd print
Model: SanDisk Cruzer Blade (scsi)
Disk /dev/sdd: 4005MB
Sector size (logical/physical): 512B/512B
Partition Table: gpt

Number  Start   End     Size    File system  Name  Flags
 1      1049kB  4003MB  4002MB  fat32              msftdata

Using gparted I changed the flag from msftdata to boot and ran the  script again, the output changed and looked like the one below:

sudo parted -s /dev/sdd print
Model: SanDisk Cruzer Blade (scsi)
Disk /dev/sdd: 4005MB
Sector size (logical/physical): 512B/512B
Partition Table: gpt

Number  Start   End     Size    File system  Name  Flags
 1      1049kB  4003MB  4002MB  fat32              boot

I then went back to my Windows 10 E6220 laptop, inserted the USD drive, turned on the power and hit f12 to enter the one time boot menu. In the UEFI boot options there was a new option UEFI: INT13(,0c81) which I had not seen before. I choose this option and the grub menu came up and I could run Ubuntu from the USB drive.

Now on to the next step to set up a dual boot with Windows 10 and Ubuntu.

At least I now know that I can install Unbuntu on this PC if I need to.

I hope this helps others

Much more difficult than the none UEFI old systems I have used in the past.