Whirlpool dishwasher

Watch the light closely. If it blinks 7 times then pauses, this indicates a heater or door latch issue.
Press the following buttons in sequence: Hi Temp Wash, Heated Dry, Hi Temp Wash, Heated Dry, Hi Temp Wash.
If this doesn't work, check the tech sheet. (should be stuck to inside of the bottom toe panel)

All lights should illuminate then a diagnostic sequence will start.
Listen carefully, as soon as you hear the water begin to fill, open the door and feel the heater. if cold, check the heater for continuity (should be around 10ohms)
Also, bend the door catch on the dishwasher tub downward, this will engage the door latch better. Don't bend too far as it will hit the door while closing.