DIAGNOSIS The smell is likely stuck in the grease filter or has seeped into the charcoal filter (if you have recirculating mode enabled). This model has a dual filter system, and odors can linger in both.
FIX Remove the aluminum mesh grease filter and wash it in hot, soapy water with a degreaser (like Dawn). Let it dry completely. For the charcoal filter (located behind the grease filter), you cannot wash it. It must be replaced. To access it, remove the grease filter, then push the tab on the charcoal filter holder and pull it down to remove. Install a new, compatible replacement charcoal filter.
IF THAT DIDN'T WORK If the smell persists after replacing the charcoal filter, it may be in the ducting. Wipe out the interior cavity, especially the ceiling where vapor collects, with a mixture of water and baking soda or white vinegar. Run a bowl of water with several lemon slices for 5 minutes to steam-clean the interior.
HEADS UP The charcoal filter is not reusable or cleanable. It should be replaced every 6 to 12 months for optimal odor reduction, especially if you use the recirculating vent mode frequently. Using the microwave without it can reduce venting performance.