If USB is fixed, why does it boot Sansa FW?
 

When I plug in a USB cable while the Fuze v2 is off, why does it boot up into the original Sansa firmware instead of Rockbox?

It's working in the current build, not the release

http://www.rockbox.org/wiki/SansaAMS..._44_ClipZip_41

You might also need to update your bootloader as well if you're still running the pre-USB one.

Thanks guys.

I'm afraid I'm a bit stuck at the moment. I downloaded the latest Rockbox Utility, then loaded the current build. After rebooting and then pressing a button or two (I think I went into the database), I've gotten an error:

Undefined instruction at 34EA0000

I can't seem to turn it off, and it's no longer seen on the USB connection. How do you recover from this?

Reboot and check the file system for errors probably.

Edit: Do you mean holding power doesn't reboot it?