I have a a 3G 15GB Ipod that stopped working. I replaced the battery with a battery from Sonnet. Now, the when I turn it on, I see the Apple for about 10 seconds, and then it switches to the folder with an exclamation point, and then goes back to the Apple quickly. When I plug it into my Powerbook, it stays on the folder for a while, and then goes to a screen that says "Disk Mode" at the top, with a large check mark, and "OK to disconnect." When it is plugged in, it accepts a charge, but my computer does not recognize it. Is the iPod dead? What is Disk Mode? Can I get out of it? (I'm using a 12' 1.5 PB with 512MB of RAM).