Microwave won't start

Jo. you may have to remove the hole cover, to access inner latch mechanism, where you can manipulate the latch with long screw driver.*** before attempting this, unplug microwave for an hour***
press the helpful button. link below may help...
Microwave Door Won Open

You may have a problem with a door switch or door switch mount, or there may be a shorted relay on the control board, which can easily be repaired.
Our help file on door switches is here, and the Advantium 120 service manual is here.
You can order GE parts from the Pros here.

see this causes and fix it. God bless you
Open Lever If the microwave door won't open the open lever might be broken. This part can be replaced separately.

Door Spring If the microwave door won't open the door spring may have broken. The door spring is located inside the door and keeps downward pressure on the door hook.

Door Latch If the microwave door won't open the door latch might be broken. The door latch is inside the microwave. The door hook, which is part of the door, engages with the latch to keep the door closed during operation. If the door latch or actuator breaks the door may not open.

Door Hook If the microwave door won't open the door hook might not be releasing properly. The door hook is installed inside the door and normally releases when the door is opened. The hook is made of plastic and will break over time. When this happens it will need to be replaced, it can't be repaired.

Button Spring If the microwave door won't open the button spring might be broken internally. The button spring can be replaced.
Button If the microwave door won't open the button might be broken internally. The button can be replaced.

Handle Actuator If the microwave door won't open the handle actuator might be broken. This is a plastic part which can become brittle over time. This part is connected between the door button and the door latch assembly.

Page 3 of the exploded view here shows the door open parts 24510L and 250201 (or 23551B if your full model number is YKCMS135HSS).

What look like part numbers seem to be reference numbers.

For further help you will need to contact Kitchenaid Canada here.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

check the hooks and door release button and repair or replace, when this is broken, the switch is not close the microwave will not START.
SEE the diagram
God bless you

It sounds like one of the door switches has become defective, each must be disconnected on the one side and tested with a digital meter using the ohms scale.

It is one of two things, a defective door switch, or the keypad control board has failed.

One or two of the door switches has failed, replacement only option, consider price.

One of the door switches is defective, caused by a build up of food particles or normal ware, to correct this a professional will need to identify the problem and replace it.

That truly sucks. Microwave door laches are quite complex. A double safety mechanism is in use and the door actually locks shut. Safety, safety. We wouldn't want you to microwave your head.
If you are going to be opening the case, unplug it and let it fully discharge. The voltages in a microwave are out of control. Keep all screws (use tape) and fully reassemble when you are done. Every part of the machine is needs assembled to keep the microwaves inside.
Smile. It could have happened to all of the locks on your house -- simultaneously. Now that would really **** :o).