There are multiple ways to reset the fault, including a logic input assignment and communication network. But an easy way to reset a fault is to remove power from L1L2L3. Allow enough time for the display to go completely blank and then wait another 30seconds. Apply power. If the fault appears again, it means that the VFD has refaulted.
The following video demonstrates how to configure a logic input fault reset function on the Altivar 212: