The short answer
A Criterion microwave that will not start is far more often refusing than broken, because it checks its door, its panel and its supply before anything happens. On this class the usual cause is no power reaching the oven, with a child lock or control lock left engaged next to rule out, and neither needs a tool.
What you actually observe
- Completely dead with no display at all — A supply question before it is an oven question.
- It works sometimes and not others — Intermittent behaviour points at a latch or a circuit rather than a board.
- NEAR MISS: it runs the full time and the food stays cold — That is a heating failure and it has a different page and a different cause list.
The causes, most likely first on this brand
- No power reaching the oven — A tripped breaker, a socket that has failed or a plug worked loose all present as a blank display, and a microwave is often on a circuit shared with something that trips it. Ranked first on a Criterion unit: a countertop oven on this brand is moved and re-plugged often, so the connection at the socket is the first thing to fail.
- A child lock or control lock left engaged — Most ovens can lock their panel, and a locked panel accepts nothing at all, which from the outside is exactly what a failure looks like. Ranked second here: the lock on these panels is a single long press and it is triggered while wiping the panel down.
- A door latch that is not satisfying all of its interlocks — Ranked third here: a light door on a contract-built oven fills its catch recess with crumbs quickly.
- A time entered but start never pressed — Ranked fourth here: last, and the display tells you in a glance whether it is counting.
Check in this order, and why this order
- Try another appliance in the same socket and look at the breaker — A standard household branch circuit is tested this way in a minute.
- Look for a lock symbol or the word lock anywhere on the display — A lock indicator is the commonest reason a working oven appears dead.
- Open the door fully and close it firmly, listening for the catch to seat — A door that closes softly and silently is not reaching its switches.
What an owner can safely check
- Reset the breaker once and plug something known-good into the same socket — If the breaker trips again immediately, stop and call rather than resetting it repeatedly.
About 10 min
- Hold the button marked with the lock symbol for several seconds to release it — The combination is on the panel legend or the control guide.
About 5 min
- STOP HERE if the next step needs a meter on live terminals or a panel off — That is where an owner check ends and a service call begins.
Before you open anything
Safety
Unplug the oven or switch off its breaker before cleaning anything around the door catch, and never remove the outer cabinet: the capacitor inside a microwave holds a dangerous charge long after the power is off, and that is true even of an oven that has been unplugged for days. Never defeat or tape a door interlock, and never run the oven empty. If a breaker trips twice on this appliance, leave it off and call.
When to call a technician
Call once the supply, the lock and the door catch are all clean and the oven is still dead, because everything past that point is behind a cabinet that must not be opened by an owner. Call immediately rather than resetting again if the breaker trips a second time. Bear in mind when you decide that this is a retailer house brand built by a contract manufacturer, so parts come through the retailer rather than from a brand service network.
Nearest pages of this class
What this page does not cover
This page covers the Criterion microwave as a class, not one family or model line. Panel legends, lock combinations and interlock arrangements all change from build to build and are deliberately not here. Where a family or model page exists for your oven, it is the more specific answer and the one to read first.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
