Yeah you've got an NT board and Iview board setup for Bally ACSC. Can't say they are rare, we've got tons of the damn things. That's all first generation stuff.
If you have any questions about it pm me. The iview link down is telling you the iview board (smaller one on top) isn't communicating with the NT board. If it's been without power for a while the battery will discharge on the NT board, and powering it back up will give you that error. Unplug power to the NT board only, then plug it back in and it'll clear that error. If the battery is dead you'll have an "Update Required" error, and you'll need to find some way to reload the board. Otherwise it'll go into a "slot not rating" since it's not connected to an ACSC system.