How to gain access to VNXe3100 without IP address

Hi,

I have an old VNXe3100 unit that I started to configure over a year ago, and have no idea what the IP address is set to.  I have held in the reset button in the back, but I don't even know if I am on the same subnet as the unit.  How can I either discover the unit without needing to be on the same IP subnet, or reset to factory defaults with only physical access?

Thanks!