All-wheel-drive light stays on?

The car has the all-wheel drive light yellow and on steady. She had the fluid changed in the I’m not sure that driveshaft not the transmission fluid maybe the rear trans axle. Light is still on and now the car is stalling no check engine light on. RPMs are very low. Before I checked it with the OBD sensor I have and nothing. I’ve never seen anything like this before. Always has problems. I thought maybe the car is in limp mode. And the car is not in front of me. She has an appointment but what do we do until then? Any advice would be helpful. I’m pretty much lost.