My Leonardo suddenly stopped mounting on any of my computers. I was working with it, uploading sketches just fine, then during one of those uploads, it reset, the computer made the disconnect noise, and it never came back. Now when I plug it in, the computer first makes the USB insertion noise, and I can see it show up under Ports in my Control Panel. It has the glowing light on it and after a few seconds it turns into a solid green light. However at the same time, the computer makes the disconnect noise and it disappears from the Ports list, basically as if I disconnected it. I tried it on several computers and they all do the same thing, it shows up briefly, then disconnects.
What could be causing this and is there something I can do assuming it's not fried?