Dish washer does not power up

The major thing to check are:

Power from the house

Is there power getting to the dishwasher? This can be difficult to test, because dishwashers are usually wired directly to an electrical circuit, rather than plugged into the wall. But at least check for a blown fuse or a tripped circuit breaker.

Door switch

The door switch is important because, if it's defective, the dishwasher won't work at all. To reach it, you need to remove the control panel cover, or sometimes the interior liner of the door. If it's defective, you need to completely replace it.

Wiring

Often the main wiring connection from the house, at the dishwasher, burns and breaks the connection. If that's the problem, the wires must be repaired/replaced as necessary. If that's not the problem, check the wiring to the door switch, the wiring between the door and the lower part of the dishwasher, and the wiring to the timer. Repair any broken, burned, brittle, or defective wiring, using the proper appliance-grade wire and connectors.

Timer or selector switch

Although it's uncommon, the timer or the selector switch may be defective. If so, you need to replace the defective part, because neither of these can be repaired.

Please tell us the make and model number for further assistance.