Diagnosis
The main control board isn't getting power. The most likely cause is a failed thermal fuse on the blower housing.
How to Fix It
Unplug the dryer. Remove the back panel. Locate the thermal fuse on the blower housing. It's a small white disc with two wires. Test it for continuity with a multimeter. No continuity means it's blown. Replace it with part DC47-00019A.
If That Didn't Work
Test the door switch next. It can fail completely and block all power. It's located inside the door opening. Bypass it temporarily to test. If the dryer starts, replace the door switch.
Heads Up
A blown thermal fuse is a safety device. It blows because of restricted airflow. Clean the entire exhaust venting from the dryer to the outside wall after you replace the fuse.