My Kenmore HE 3t washer will not start. It has power, because all of the buttons will light up when I push them. I can select the cycle I want, but when I push and hold the start button, nothing happens. The door closes securly. Any suggestions?

Electronic controlled appliances are not easy to diagnose for the average person unless you are sharp in the electronic field. At times just unplugging the washer for 15 minutes and then restarting it again at times resets the controls.
Also in the back of the "Users Guide" there is usually a troubleshooting guide.
If you have no luck you may have to get tech to come out, but try to find out if he is proficient in diagnosing your model and brand machine.
Good Luck!