When you say it cut off after 15 minutes, did just the heat cut off or motor and heat? You say it restart after a little while. It started by itself? Or you had to wait and pushed start button to restart? Doesn't matter which wire to which terminal on heater. Do you have multimeter and experience using it?

Eric

Check continuity on the thermal fuse (two blue wires). This is in the motor circuit and if bad, dryer will not start. Thermal fuses do not reset so the fact that the dryer just shut off and couldn't be restarted til later could be that the motor overload tripped. It will reset itself after it cools but you would still have to press the start button to start it. An overheating dryer is usually due to airflow problems because of too much lint. You need to make sure all the ducts, external and internal, are clear including in the blower housing and that the blower wheel is clear. A faulty operating/cycling thermostat can also cause overheating. The best way to test it is on a hot plate. It should open when it reaches 155° and close again when it drops to 130°.

Eric