So that sounds like the calibration procedure may not have been performed quite right and the AOA ALWAYS thinks it is stalling. Try going into the AOACAL menu in flight. Don't press anything after that. Vary the aircraft from cruise to slow flight. Does the AOA indication change? It should. When in calibration mode, you're seeing somewhat of a 'raw' version of the pitot and AOA inputs relative to each other. If it doesn't change when doing this, then the next place to look is at the plumbing to the AOA side of the pitot probe.