Vehicular systems located in commercial passenger vehicles are tested and maintained for operational effectiveness. This patent document describes techniques to perform secure testing on multiple seatback monitors that are located on or in seats in a commercial passenger vehicle and that are associated with a vehicle entertainment system. An example method can determine whether multiple sets of usernames and passwords received by a device authorize a person operating a test-related software on the device to securely test one or more groups of multiple seatback monitors in the commercial passenger vehicle. The example method can also enable selection of a group of multiple seatback monitors that can be specifically tested.