This whole thing is very sad to hear.... why? Because it is the SAME thing that is wrong with mine.
I have spent the last two hours 
looking online trying to find an answer to what is wrong with my drive. I am not sure when I got it, I got it at Costco, so they know when, but it was at least 6 months ago... I was using mine fine the other day, then last night I turned it on and NOTHING. The only thing it does is beep for about 5 minutes, then stops even that. I searched the whole "Knowledge Base" and several sites....
What I have discovered is that this seems to be a problem with these drives. 
Seems that they "lock up" and lock you out for no real reason, after while. That there is a firmware fix, but unless you know about the problem ahead of time, you are basically screwed as you only find out when your unit breaks.
Another thing I found out is that you can't do anything to make it work. You can get the data recovered, at a great cost to you, even though Seagate seems to know of this problem, thus I believe THEY should foot the bill when it inevitably happens to your drive. And that before you send in your unit for replacement, make sure to get your data off or it is gone forever.
The things I've read in the last two hours have saddened me. I bought the external drive not so that it would make it easier to go from one computer to another, but because I've often had computers break down, or get old and get a new one, and it takes so much to try to save my photos and stories and all my work that I wanted to have it in one place that I knew it was safe. Now the cold hard fact has hit me that nothing really is "safe". The external drives are just as likely to screw you over as the internal ones. And where it was inconvenient to get the data off the older computers, it never cost me to do it. Now with the external ones, ones they knew had a problem with locking you out, it's going to cost me to get my data and be a total pain in the rear to get a new external one. Though now I'm more leery of doing it, because when that one locks up, it'll cost me again. I only hope that there is a way that I can recover the data without it costing a small fortune, as I'm disabled and on a fixed income.
I have put in a "ticket" to find out what is wrong with mine... but then found this and other forums along the same line of "what happened? I didn't do anything, but it's not working suddenly!". So, I can see that I will have to call tech support, or go through what ever channels I need to in order to get the "okay" to crack my case and get the information off it, then get it replaced.
You weren't sure what as wrong with your unit... if it's the same thing that is what happened to mine, it's not your fault. 
If it's the thing that I've been reading about, it's a problem Seagate knew about but don't really care about. The units lock up for no reason, the firmware being bad and needing updating as soon as you get the unit. Though I also read that that isn't a guarantee it will work, just that you have a better chance it won't happen to you.
Best thing to do... get the "ok" to crack the case and recover the data. 
Then get it sent in and replaced. Then as soon as you do, make sure your firmware is as up to date as possible, because your replacement unit won't have the updated firmware either (so I read at least). Then finally, send up a prayer to what ever God you follow that it doesn't happen to you again. Looks like that is what I'm going to have to do... And I really needed some of the information I had on mine today. Talk about a kick in the gut!
Good luck! 
