Have you tried to turn the unit off by the circuit breaker? Or unplug the unit for 3-4 mins?
On the inside of the dryer is a moisture sensor which looks like two metal curved bars inside the front of the drum, typically in the housing for the lint filter or to the side of it.
If these steps do not resolve the issue then the unit will require service. You can use the following link to find a service center near you to do the repair. http://www.samsung.com/us/support/service/location.