More than likely the rack-n-pinon is electric as well and that's what went out. Seen it before and will more than likely need will need to be recalibrated when a new unit is installed. Most are turn all the way to on side then the other and back to straight. This is where I would start looking.
It's just like one on a hydrologic system just electrical. But any rack-and-pinion system takes a lot of abuse and wear.
Check for a blown 50 amp fuse in the PDC, there are two next to each other they both are for power steering one will blow and make the steering inop. Usually a sign of a bad component of a loose/dirty ground