ipod non mounting...how to restore?

I've done a search of the forums but cant find a thread that matches my iPod problem exactly, so before I send it in for repair/replacement under warranty thought I'd see if the combined knowledge here can come up with any solutions.
Right, it's a 4 month old 15gb iPod with dock and it wont show up in iTunes or the Finder on my iMacdv 400 running latest 10.2.8 . Even though I've trawled various forums, including Apple Support, I can't seem to find a way to restore it if it doesnt mount. Here are the things I've tried:

1) repairing OS permissions.
2) fsck in single user mode.
3) mac janitor.
4) running Disk Utility, doesnt show up.
5) Go to folder/volumes...no show.
6) Terminal- /mount.
7) Restarting Mac while iPod FW plugged in.
8) Resetting ipod, then pressing FF and RR which shows a 'tick' icon with 'ok to disconnect underneath rather than 'Do not disconnect'.
9) just resetting serveral times.
10) Using my wifes dual G4 at work- same no mounting issues.
11) iSync- shows in the menu but doesnt update due to 'cannot find device'- odd.
12) Testing both FW ports on iMac using Lacie d2 ext.drive and Sony DV camcorder...ports work fine for these two.
13) Checking all connection for dirt- clean as a whistle.
14) Pressing a multitude of buttons on the iPod, longshot I know.
15) Running the battery down.

Well, thats all i can remember of the things I tried. Weird thing is that it recharges. Any suggestions would be gratefully recieved. Hopefully they won't repair it but replace it with a new 20gb...fingers crossed.