Try hooking up a computer monitor to the VGA port (it's behind the plastic piece that covers the front of the BFT). As long as you're not getting a disk error, you're HDD should be OK. However, if the BFT is bad, I can't remember if the VGA ports works.
Either way, you'll have to call Nortel. When the BFT goes bad, there is no network access, no Call Pilot, no serial port connection, and no dial up modem access. Fortunately, the BFT is easy to replace and everything should come up once it is replaced (assuming the HDD is good). Good luck.
