Quickly double-check, is the outlet getting power? Do you have too many things plugged into the same outlet or circuit?
Check operation in another outlet.
Did the unit accidentally get wet or submerged?
Save yourself the freight fees and let it fully dry out before sending it in for repair. We have had units returned for repair and with a few days of dry time/transit they started working again.
Has any food waste come in contact with the thermostat?
This can cause the unit to stop heating.
Do you use the unit as a water-bath?
Using treated or softened water and air drying during non-use is a great way to extend the life of the water vessel; prevents water from leaking through a corroded pinhole onto the electrics within.
Is descaling part of your scheduled maintenance?
Over time, lime scale can build up on the unit and cause it to stop working.