Please don't take offense, I'm going to baby-step some of the errors people are making when trying to update.
Load your flash drive on your PC. When you browse the drive, does the update folder icon have a zipper on it? What does it say under type? Lots of people have managed to try to use files named update.zip.[some random file extension] where the .zip is actually just part of the filename and not the file extension, which just won't work
Now you mentioned that you're using a stick with a light, that's good since it let's you know it's doing something.
When I flash my Edges, I hold the buttons down until the second dot appears and when it does, if an update is happening (any update), a small white cursor appears in the upper right hand corner of the tablet with dot #2.
The last thing that I've done and seen others do is accidentally put the dingo file on the drive instead of the ermine.
And you could try to re-download the file in case it got corrupted somehow.