When the switch is loading check to see if there is an option to boot from the second partition.
I believe you should have 5 seconds to choose before booting to the default partitions.
If this does not work I would return the switch.
This one, nor the new one that was purchased, allow me to choose a different option. That being said, the new one boots properly. The other switch was returned.
Is there a u-boot select pin inside of the switch?