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Official-source symptom guide

Microwave Will Not Start: Power, Lock and Door Checks

A microwave that will not begin a cook cycle may have no power, an active Control/Child Lock, Demo mode, a timer-only function, an unclosed door or a condition that needs service. Keep troubleshooting entirely outside the cabinet.

What can cause this symptom

  • The outlet, GFCI, household fuse or breaker is not supplying power.
  • Control Lock / Child Lock is active.
  • Demo mode, Timer mode or another non-cooking mode is active.
  • The door is not closing or latching normally because of an obstruction or damage.
  • The model requires a normal Start input after setting the cook function.
  • An internal control, interlock or electrical condition requires qualified service.

Safe checks in order

  1. 1

    Separate no power from no start

    • If the display is blank, confirm the cord is firmly connected to the correct wall outlet where accessible and check a GFCI or household breaker only from a dry, safe location.
    • Do not use an extension cord, improvised adapter, inverter or generator unless the exact manufacturer documentation explicitly permits it.
  2. 2

    Check normal controls

    • Look for Control Lock / Child Lock, Demo mode, Timer mode, LOC, L, a padlock symbol or another model-specific status.
    • Use only the button sequence in the exact owner manual. Do not force buttons or open the control panel.
  3. 3

    Check the door from the outside

    • Remove visible food debris or obstructions from the door-contact area using the approved cleaning method.
    • Close the door normally. Do not slam, pry, shim or bypass the latch or interlock.
  4. 4

    Reset power once only if manufacturer-supported

    • If the manual recommends it and the electrical area is dry and undamaged, unplug the countertop unit or switch the dedicated breaker off for the documented interval, then restore power once.
    • If the breaker trips again, the door is damaged, or the unit still will not start, stop and request service.

Brand and model differences

  • LG documents door checks, Control Lock and a brief power reset before service, with model-specific unlock controls.
  • Whirlpool separates direct wall power, Control Lock, Timer/Demo behavior, door closure and normal Start input.
  • Some models intentionally require the door to be opened and closed again after it has been closed for several minutes before a cooking function can begin.

Actions not recommended

  • Do not bypass, tape, shim or electrically defeat the door interlocks.
  • Do not open the cabinet or control panel to look for a fuse.
  • Do not repeatedly reset a breaker that trips again.
  • Do not run the unit with a damaged door, latch or seal.

When to request service

  • Power is available and normal lock/mode/door checks do not restore operation.
  • The breaker or GFCI trips again.
  • The door, latch, seal, cord, plug or outlet is damaged.
  • Any next step would require internal fuse, switch, control or wiring access.

Official manufacturer sources

Reviewed: September 22, 2026.