osso-usb-mass-storage-enable.sh is exactly the script You need to use, for "exporting" things into mass storage, manually. Check my signature and TrueCrypt thread - there is instruction, how to use this script (with given parameter) to export other partition into mass storage, instead of MyDocs (in case of mentioned instructions, it was about exporting - transparently for desktop - encrypted partition from n900 to desktop, where n900 does all decrypting work, creating de facto encrypted pendrive funcionality - but, it shouldn't matter for Your case).

I absolutely understand Your will to learn and fix it Yourself - personally, I never did reflash, fighting with (even most irritating and troublesome) problems manually, always managing to solve them, somehow (wouldn't be possible without help of wonderful people, here).

I've suggested backup and reflash, only because it's extremely hard to tell why Your device is in such state. If You can usb hostmode, it's definitely not hardware problem, so something - program or manual tweak - pushed device into such random state. Usually, owner know - even slightly - what might be responsible, so it's easier to pin out the problem.

/Estel