Microwave not working. Our GE Spacemaker Microwave model JVM1650 will only run for a couple

Question

Our GE Spacemaker Microwave model JVM1650 will only run for a couple seconds after you press start or and express key. It shuts down , lights up all the characters in the display, then displays the GE welcome , then displays the set clock. the unit is about 3 years old.The fan comes on It does not seem to run long enough to heat up and shut down due to heat build up. Is there a reset switch? Any suggestions??