I have had a few with the hard drive problems That is why I went ahead and invested in a USB-to_Zif adapter. It allows my to check the drives for faults etc. Handy little tool to have. The other issues that I had with 4th G iPod always happened after battery replacement is the issue that you are having. I usually charge my iPods on a fire-wire wall charger for about 2hrs before I do anything else with them. Can you get your iPod in disk mode or diagnostic mode at all without being plugged in to your computer.
Just in case, here is the how to. The diagnostic might help you out to determine what is not working.
Fourth-generation iPod, iPod Photo, and iPod mini: Click-wheel iPods don’t offer a button combination to scan the hard drive. Rather, you must access this function through the iPod’s Diagnostic screen (which I explain at great length later in this chapter). Use this combination when you want to check the integrity of the iPod’s hard drive. This test can take 15 to 20 minutes, so be patient. Be sure to plug your iPod into the power adapter when you perform this test so that the iPod doesn’t run out of juice before the scan is complete. If the scan shows no problems, a check mark appears
over the disk icon. To return your iPod to regular use, press Play.
- Diagnostic mode.
First three generations of the white iPod: Reset the iPod. At the Apple logo, press and hold Previous, Next, and Select.
Fourth-generation iPod, iPod Photo, and iPod mini: Reset the iPod. At the Apple logo, press and hold Select and Previous. Diagnostic mode includes 16 tests for the first three generations of the white iPod, 19 tests for the iPod mini, 21 tests for the fourth-generation iPod, and a mess o’ tests for the iPod Photo that may help you determine what’s wrong.