Try booting the USB on another machine. If you browse the contents of the flash drive, you should have a few folders (sources, etc.) and a few files (setup.exe, etc.). Did you follow the USB prep instructions EXACTLY as I laid them out? 
I have try to install Win server 2012 on a Poweredge 1950 creating a bootable USB and a DVD but either way is not working, I have follow several web options like setup boot process for USB and to boot from CD but no matter what I do on the USB it just hang and with the DVD will skip it, it wont even try to read it. Any help is much appreciated 
Install windows server 2012 on Poweredge 1950