USB Boot Menu is All Gibberish

All right, so....
I rebuilt the entire boot USB disk (I'm using Windows 7 x64) as admin.
I used the "install BCD" option like in the docs. In fact, I have done as what is in this tutorial (except I have added multiple ISO files to choose from in the menu).
and I still get gibberish when the computer boots with the USB disk.

I'm trying to boot a Dell Optiplex 7010 and I've tried both UEFI boot and Legacy boot non secure.

What's going on, and why doesn't this work?
Following are booting method for your Dell Optiplex 7010 Model: For detailed explanation check Dell OptiPlex 7010 Manual. Following are short term points:
  • Boot mode should be selected as UEFI (Not Legacy)
  • Secure Boot set to Off. ...
  • Go to the 'Boot' tab in the BIOS and select Add Boot option. ( ...
  • A new window will appear with 'blank' boot option name.
  • Name it "CD/DVD/CD-RW Drive" ...
  • Press < F10 > key to save settings and restart.
  • The system will restart.