[martin_fierro]

I have an HP-Apple 4th Gen iPod.

Me too -- 40 GB from Costco.

Let me know if you're able to access the diagnostics -- I couldn't.

[CarrotAndStick]

I was able to do it. Cheesy interface, that diagnostics menu.

1... First put the 'hold' switch to 'off' position (the
white indicator will be visible).

2... Press 'menu' and the center button together for 12
seconds. You'll see the apple logo appear. Now before
this logo disappears, hold down the 'previous track |<<'
and center button together for another 12 sec. You'll
see the iPod perform a "RAMPASS" test.

3... Press the 'play/pause >||' button to enter diagnostics
setup.

4... You'll see a menu, which can only be navigated by
pressing the 'next track >>|' button to go down the menu,
and the 'previous track |<<' button to go up the menu. The
center button is to select the chosen item from the
menu. The touch-sensitive scroll function is disabled
in the diagnostics mode.