If you took one drive out and put it on the other, the RAID controller will start rebulting the drive with the data from the previous one.
It looks like you have wiped the drive. As you still have another drive, If you put that in the working media vault, on its own it should access the data and rebuild it.
It sounds like you have two problems. A failed drive and unreachable MV. You say that you can ping the MV but not reach it using the admin webpage. Can you try to take it off a static IP and let it get a dynamic IP and see if it's now visible?If still no luck can you try changing the IP to another static and see if that helps?The drives are just storage. Any network configuration is done by the MV adapter.
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