yes, many FW connections are notoriously risky, extending the 'hot-pluggable' into frying domain. We burnt a lot of disk cases, until we realized it wasn't the cheapo chinese built quality, but the connection...
In that case the device isn't visible to the OS and wouldn't show up in system info anymore.
If you 'see' the interface connected, there's still the chance something is damaged, but at low probability - and tracking that down to the source is close to impossible.
You can measure voltages at chip's supply pins (look up the diagram), but it's quite fiddly for boards are sealed and may not make immediate connection with the probe - and since the circuit is 'live' you shouldn't slip.
After all I'd rather discourage the procedure. You don't seem familiar with cuircuit board handling and what would you do if you find a wrong voltage ?
Without a circuit diagram and you'd have to figure out the design yourself.
To check the unit it doesn't need OS-9. Any other computer with FW connection would do, so take it to a friend, a 'friendly' store or wherever.
Guessing from inside pics I've seen, it's not a particular great piece of audio technology, so you may take the unfortunate event as an opportunity to 'upgrade'. Old digital audio gear is dead cheap today.
