Does it try to boot at all. You might want to try checking the partition and seeing if it has been set as a boot able partition. If you don't have a partition program you can download Easeus's partition master which works great and is free.
I have been creating boot able flash drives for the past two years and have had several problems with programs that create the flash drive not setting the partition on the flash drive as being boot able. Using Easeus and setting the partition as being the primary, active partition usually solves the problem. Of course that would have to be the problem for this fix to fix it.
Worth a check though; the Easeus program is a big help if you are going to create boot able flash drives or boot able SD/HC cards. Can't tell you how many times it has helped me fix problems.fdalbor