Just another thought.
By any chance was somebody already online with it perhaps ?
I seem to remember "something along the lines of" that the (older at least) Micro800s, once connected to the PC. If the connection is interrupted without a specific process of save and "go offline" rather than just cutting the online connection, it needed a power cycle to allow another connection. I had one older one here that seems to lock me out like this, just be a pain but always allowed me to connect after some fiddling... It was a long time since I touched it, but last time I used V13 and had no hiccups.
I assume you have already had somebody there power cycle it, or perhaps it is in production now cant be interrupted.