On the 'Back side' (inside) you will need to find the box that holds the relay, With power OFF AT THE CIRCUIT BREAKER. to the water heater check the leads to the heater with an Ohmmeter.. I'm guessing open circuit. If you see a good circuit (The resistance will be like .1 ohm) then with the cover off, and the meter .. elsewhere.. and the tank cool, and the control switches off, REstore the breaker to ON, and then observe the relay as your partner activates the ELECTRIC switch.
It should pull in within 1 minute, if not.. Control board.
With the cover off the relay box.
