Typically, that would be caused by failure of a cheap chinese control board. In fact, failure-prone chinese control boards are at the heart of virtually all premature failures of modern appliances. They usually only last just long enough to span the warranty period.

There should be an electrical schematic diagram attached to the back of the unit. You may be able to use that to identify the faulty part. Don't be surprised if the replacement board costs alot more than it's size and simplicity might indicate.