The password requested is the admin password for the device, not the AA PIN. The default is "admin" but check the OBiTalk portal for a changed setting. Use the keys corresponding to letters, e.g. 23646 for admin.
If that doesn't work, temporarily set a compatible static IP address in your PC and access it via the web interface.
If that doesn't work, either, you will have to do a hardware reset to recover. With luck, you will have a config backup, otherwise you'll need to re-enter all settings.