Sounds like the ESC is armed...? I'm not sure why else the ESC would respond like that. It does mean the interface is working and tried to put it into bootloader mode via the CLI. Is the green esc light on?
To test directly, download PUTTY, select a serial type connection, enter your COM port and 230400 for the speed, then connect. You should get a > prompt from the esc. Type help and see what happens. Then try typing bootloader.
-Max