I’ve saw this problem happen with computers also. You are correct in that the system is recognizing the attached device and trying to boot from it. The only way to get aroud it is the way you describe or disconnect the drive from the Sentinel before rebooting or powering up. I personally have one drive that causes this problem on my system.
Sometimes it is just a specific combination of the type of BIOS the system has and the type of chipset or drive that the enclosure uses.
