With a recent client, we had to re-register the StorSimple physical appliance to a new instance of StorSimple device manager instance, the old instance was deleted and no longer available on Microsoft Azure (ASM).
If you attempt to run Invoke-HcsSetupWizard on the appliance, it would error with the appliance is already registered to another instance and the only way to register it to a new instance is to factory reset the device.
While resetting, the device hang up on phase 3 and wouldn’t go past that stage. After speaking to Microsoft Support, they have advised to shutdown both controllers and re-attempt to run the factory reset again which was successful in this case.
Just keep in mind that you will be losing all your device configuration and any data that you have accumulated on the device after the reset, ensure you update device after the reset.