OpenBoot may not operate correctly after the operating system has begun execution. (For example, after Stop-a or halt.) This occurs when the operating system can modify the system state in ways that are inconsistent with continued OpenBoot operation. In this case, you may have to power cycle the system to restore normal operation.
For example, suppose you boot the operating system, exit to OpenBoot, then execute the probe-scsi command (described in "Booting and Testing Your System"). You may find that probe-scsi fails, and you may not be able to resume the operating system, or you may have to power cycle the systems.
Re-execute an OpenBoot command that failed because the operating system has executed: