If you smell burning, stop using it and disconnect the power only if it is safe to do so. If there is active smoke, flames, or you cannot get close without risk, move away, alert others, and contact emergency services.
Do not run another test cycle
Do not open panels, lean in to smell it, or move the smoking appliance. Also do not pour water on equipment that may still be connected to power. Recovering the laundry can wait until the situation is safe.
Burn marks, electrical crackling, and overheating connections are signs that should not be ignored, according to the Electrical Safety First guidance for washing machines. It is not enough for the smell to go away as it cools.
Information that helps later
Once there is no longer an emergency, keep track of the stage when it happened, any sounds beforehand, and visible marks without taking anything apart. The smell may be like rubber, plastic, or electrical material, but it does not reliably identify the source.
Rubbing can affect the belt and pulleys or the seal; a motor or connection problem can also cause overheating. These are possibilities for inspection, not a list of parts to replace.
Before using it again
The technician should confirm the cause and any related damage. If there was an electrical trip, include that detail. Do not clean to hide marks or use scented products: if the smell disappears, that does not prove the repair is valid.
Leave the appliance unplugged and clearly out of use until it has been assessed; a smoking incident is not fixed by resetting it.