Help used micro as timer but pushed start instead now wont work

Check to see if the fuse went. If negative then something is wrong with the electronic pad for the unit.

It sounds like part of the electronics driving the magnetron (yes its a real word) have failed. So you could take it back, or get it repaired, or replace it. The repair costs would be similar to buying a new one, so I would buy a new or used one, but buy a japanese brand like panasonic instead. My Panasonic micro is 17 years old and still working.

Carefully verify the door micro switches.

Micro wave as the name suggests produces heat when the micro waves aimed at an object causes the water molecules inside the object to vibrate hence producing heat.The gadget responsible is the magnetron. If your magnetron is not receiving ht voltage or receiving but faulty, then your micro wave wont work please take precaution when opening micro wave due to high voltage caps that remain charged sometimes even when it is off.check the high voltage fuse/ diode and capacitor if they are fine and the step up trans former o.k then the only option is to replace the magnetron

With micro waves, this could be a number of things. They are hard to diagnose using this forum but I'll try. There are three things you can check. One being the thermal fuse. On some models, when it goes bad it put some things out. with others it puts every thing out.
if it's good, check the mag tube (Magnatron). Most of the time, it will be burned on the end if it's bad. tube. The last thing would be the fuse. It is made of ceramic and is a 20amp. It looks like a old round car fuse but it's not. It's made just for micro waves. Honestly, if the thermal fuse and the round 20 amp fuse is not the problem, you may be able to replace the micro wave cheaper than replacing the parts.
Thermal fuse $28.99.
Round 20amp fuse $1.53
Transformer $100.00.
Mag tube $87.00
Capacitor $45.00
Go to www.appliancepartspro.com and enter your model number. This will pull up every part in the micro wave and their prices. Then you will ba able to decide if you want to replace the parts. With yours being one that's built-in over the stove. These cost more and are worth putting more into. If I can help any more comment back and I'll do what I can.
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cavity therm is bad probably, some people use the micro as a timer thinking they are using the kitchen timer and it burns out the cavity therm. get a qualified svc company to replace the therm, if it is the therm it wont heat or start or anything, if its just the timer thats not working then i suggest a new clock board.

HI, there is a inline fuse located inside the microwave ion the power supply board. check for continuity. replace the fuse if necessary. if the fuse is OK, replace the power supply board.

YES THERE IS AN INTERNAL FUSE OR DIODE YOU CAN CHANGE, BUT YOU SHOULD BE CAREFUL AN LET A PRO DO IT, YOU JUST DON'T WANT TO GET ZZZAPPPP WITH THE CAPACITOR THAT STORAGES HIGH VOLTAGE INSIDE TO PROVIDE THE MICRO WITH POWER, IT MAY SEEM LIKE A LIL UNIT BUT IT CAN HURT YOU IF YOU DONT DE-ACTIVATE IT RIGHT, NOT SURE IF THE DIODE WOULD BRING IT BACK BUT CHECK WITH A SERVICE MAN, BEFORE DOING ANYTHING I WOULD!

Try to unplug your microwave then leave it for 1 hour the purpose is to reset and drain stored current after 1 hour plug it again ,if still notworking there something wrong inside. Usually, when your microwave oven doesn't work it all, the internal fuse (thermal fuse) is blown. This fuse protects both you and the oven. When it blows,you need to replaced it or you need to have a qualified appliance repair technician replace it.

Hope it may help you;

Regards
VOTIT

The power fuse open , if open replace it don't make jumper it b
cause fire .
the power transformer builtin fuse open/
The door micro switch open /need to replace.