New config allows to reconfigure the array devices keeping the existing data.
So, tools -> New config - re-assign both disks (make sure not to assign a data disk to a parity slot) with disk2 using a SATA port and start the array, if both disk mount you're done, if disk2 doesn't mount, repeat the procedure with disk2 back in the USB enclosure, you'll then need to empty it before using a SATA port.