It looks like the hold switch on my Rockboxed iPod Classic 5.5 is knackered - it has no effect when the player is switched on or off.
I use iTunes to rip and transfer my music to the iPod. But to do this, I need to boot the iPod to iTunes rather than Rockbox, which I do with the hold switch.
Is there any other way to switch firmware on the iPod Classic 5.5?