To repair your KitchenAid microwave, remove the spacer first if the door is not closing properly. Then, firmly press Start to see if the panel is working properly, and ensure that the appliance's child safety lock is not active. Finally, undo the turntable and support, and cleanse the microwave thoroughly.
KitchenAid microwaves, and most microwaves in general, contain parts that can cause severe electrical shock or break if not handled and repaired properly. Only a trained professional knows how to fix the electrical equipment inside of a microwave, so make sure to troubleshoot the item safely and contact a service technician if you do not have the skills to fix the electrical problems you find.
The child safety lock prevents normal microwave operation to keep children from microwaving unsafe objects. Press and hold the Start or Cancel button until a tone plays in order to deactivate this safety lock.
If the rollers in the turntable mechanism are blocked, the microwave can't heat food properly. Clean the rollers with a mild dish detergent in order to get any loose food debris or other small particles out of them. If the turntable still does not turn, then the mechanism is broken inside the microwave and must be repaired by a service technician.