The dryer's lint filter does more than simply trap lint from your clothing; it also maintains heat and airflow in the dryer, removing moisture. A dirty or clogged filter will decrease airflow and increase the drying cycle and cool-down time. Clean the lint filter every time you use the dryer to ensure proper air circulation.
Heavier clothes take longer to dry because they retain larger amounts of moisture and because lightweight fabrics retain heat faster than heavy fabrics. The dryer maintains the cool-down process until the clothing is lowered in temperature after heat exposure. An imbalance of light and heavy fabrics in your dryer throws off the heat sensor, causing the dryer to stay in cool-down mode.
The issue might be the result of a power surge. Your dryer must be plugged into a grounded wall outlet, and surge protectors are unable to handle the amount of power required for the dryer's operation. A power failure resulting from a power surge causes the dryer to stay in whatever stage it was in when the surge occurred. Manually reset your dryer to restore use.
The touchscreen on the front of your Kenmore dryer includes a "Cancel" button to forcibly end the current cycle. For non-LCD dryers, press "Power" to turn off the dryer and unlock the dryer's door. Once canceled, the dryer's door latch automatically unlocks to allow access to your dryer's load.