Summary
Multiple entrance stations on the system none of which can enter programming mode. None of the entrance stations share the shame dip switch configuration and power to the GT-BC has been cycled.
Solution
On an expanded system, the 5 entrances can have their ID set as 1 – 8 and wired into Common1 of the BCXB-N. If any of them are set as ID #9 or greater and wired into common1 of the BCXB-N, then that entrance station will fail as those ID numbers are reserved for an expanded system, which wires into Common2.