Samsung dryer keeps running

Our dryer will not stop turning unless the door is open or it is unplugged. The power button turns on the display and the start button begins a cycle on the display, but neither of these things are affecting the drum turning. Also the dryer is not generating the heat it usually does. It is only generating about 25% of the heat it usually does.

I would really appreciate any suggestions. By the way, I will be away from the house for a few days so I won’t be able to try anything until Thursday. Don’t these things always happen right before a business trip!