I get asked a lot about how to load the CIE (Customer Immersion Experience) MEC (Microsoft Experience Center) demo on the Surface Pro 3, hope this guide helps!
Surface Pro 3
USB thumb drive 16GB (depending on the MEC image)
Imaging time 45 minutes to 1hr and 30minutes depending on flash drive speed.
Obtain the MEC Demo ISO.
You should be able to get this from the Microsoft Customer Immersion Experience (CIE) site. You will have to sign up if you do not have access.
Once downloaded, format your USB stick with Fat32
If you have a USB stick that is Larger than 32GB use a 3rd party formatter tool from the link below (windows can only format 32GB and smaller with FAT32)
Extract the MEC ISO files directly to the USB Stick.
I never had much luck using a USB imager with the ISO as it does not work well. Most of the time it does not boot or fails to load on the Surface Pro using the USB imager. Not sure what makes it so different from extracting it to the USB Drive as it shouldn't.
Turn off your Surface Pro
Press the Volume Up button and hold it, then Tap the Power button once, let go once in the bios settings.