Want to share my experience, have a 80GB Video iPod and it had the "Please Wait. Very Low Battery" message with spinning wheel for a very long time.
I would read these forums a little, try again, then leave it for a while. Also, note that my iPod would come up and function if it was plugged into the wall, but as soon as I unplugged it, it would die. When I plugged into my computer it would not show up in iTunes and would have the message I described above. As noted in earlier posts, it doesn't have enough juice to get passed this stage. That is why doing the resets seems to work. But keep reading as just doing the resets did not seem to work for me until I had done some combo of all the stuff listed below.
What ended up working for me was doing the reset of holding the "select" button and "menu" together. I hold hold it for 3-4 seconds, it would kind of flash, then come right back up. I would release and do it again. When it finally worked I had done it probably thirty (30) times AND I thought it hadn't worked, so I gave up and 45 secs. or so later the magical apple came up. I had tried all this before, BUT also read the next paragraph. (I had tried many times doing the resets as just described before where I reset 30 plus times, without doing the things listed below and it didn't work, that is why I place some importance on changing your battery/power cord settings, unplug all other USB stuff, try all USB ports)
Anyway, over the past 6 months I have had to get a new battery for my Powerbook G4 and a new power cord. AND, I also tweaked the performance settings under system preferences and "energy saver" to give the highest energy output or best performance or whatever it says AND i dimmed my screen to almost all the way off.
Now, I have no idea what combination of stuff helped it to to finally work, but I would try all this stuff if you are desperate. Good Luck.