Dryer is not turning on

The load is dry, yet the dryer keeps running and running. Before that unnecessary heat damages your clothing and drives up your utility bill, you may need to replace the timer or the electronic control board that isn't ending the cycle. If your dryer uses a mechanical timer and doesn't stop when the dial reaches the off position, then a failed contact in the timer is likely causing the dryer to continue running and you'll need to replace the timer. If your dryer uses an electronic control, a stuck motor relay on the electronic control board can cause the dryer to run constantly with the dryer door closed. If the dryer stops only when you open the door, you'll likely need to replace the electronic control board.
If the dryer won't turn off when you open the dryer door, the dryer door switch likely failed. Replace the door switch if it doesn't accurately detect the door being open or closed.
These tips can help you figure out what's wrong when your Kenmore or Kenmore Elite dryer spins when off. You can also use this repair help to fix your Whirlpool, Frigidaire, Samsung or LG dryer that runs when the control is in the off position.

I would say this is in the control board but not 100 percent on this. If you go to an appliance store, not a big box, they will probably help you diagnose and order the part for you if you want to do this on your own.

the cycling and the hi limit thermostats.
For continuity or OHMS. If no ohms or resistance they need replacement.

In some dryer's the control panel relies on a thermistor rather than a CYCLING thermostat to regulate the drum's air temperature by monitoring the component's resistance changes; resistance goes down as temperature increases and up when temperature decreases. Once the drum's air temperature reaches a certain level required to dry clothes, the control panel shuts off the heater. The panel will turn the heater on again and begin another heating cycle when the thermistor indicates that more heat is needed to keep the air temperature constant inside the drum

Lastly check your moister sensor. ( located inside the dryer door usually) Especially if machine seems to shut down early and clothes are still wet.
Test with a meter at room temperature and it should show continuity.
A failed moisture sensor will affect the dryer run time in the automatic moisture sensing cycle but it will not affect the heating of the dryer or the timed cycle. Which are reflected by the thermostats.

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If the dryer continues to run when you open the door you will need to replace the door switch. Here is the part to order.

This has to do with the control board failure. The control board runs every aspect of the dryer and will need to be replaced. Here is the new control board.

no,it sounds like the heating element is touching metal and as long as the timer is sending power until it goes to off it will keep heating.change out the element

Check where the dryer vent comes out and make sure that there is a good amount of air coming out. If the fan is blowing, the drum is turning, and there is heat, the likely thing is that the dryer vent is partially blocked. Check the pipe leading out. Bird's nests are not uncommon. The only other thing I can think of is that the door catch is wearing out and the door is popping open, shutting the dryer off mid-cycle. Some dryers will continue to run the timer if the cycle is interrupted and it will appear that the dryer ran its full cycle, but in reality it shut off soon after it started.

Once you open the door your wrinkle guard won't reset.

can you just leave the door open when not in use???????

Change your timer. It has a malfunction in it. it's about a 100 dollar fix. Also your start switch may be bad.