If you only reformat one drive the raid would still be in tact and the system would simply report that one of the drives is bad which is why you are getting the amber light on the front for that drive. You need to do what you did with al of the drives and then put them back in. Upon boot up with all fresh devices it should automaticaly rebuild the raid. When you enter the ip address of the unit into a web browser after a while you should see a progress bar that you can check back from time to time to determine progress. This process worked with my unit but the rebuild takes some time. I want to say it took more than a day or so to complete.
Good luck!
