Power steering pump shaft broke inside pump

Gonna sound stupid, but I've seen this happen more than once. Remove the return hose from the reservoir and check for a plastic dust cap on the pipe. They're often painted and get overlooked.

If that doesn't solve it, remove the high pressure hose from the gear box and run the engine briefly to see if fluid runs out. If it does, reconnect it and remove the return hose from the reservoir and see if fluid runs out when the engine is running AND you turn the steering wheel. If it doesn't, be sure the serpentine belt is routed around the pump correctly. The ribbed side goes around the pulley.

The return line will only flow fluid when the steering wheel is turning, not when it is standing still in any position. If that isn't happening, the control valve has broken inside the steering gear box or something has blocked the fluid port in the gear box.