Heater motor was running and could smell something burning?

Hi.

Assuming the motor still has power and ground, i would say the motor burned out and needs to be replaced.

Yep I agree with JEFFYTUNE, here is the location of the blower motor and I have included a guide to help test the blower motor power and ground.

https://www.2carpros.com/articles/how-to-test-an-automotive-hvac-system-blower-fan-motor-a-detailed

Check out the images (below). Please let us know what happens.