Electric water heater has panels located on front of water heater.
Remove top cover, and insulation to reveal thermostat and element.
Stand on dry surface, including boards or plywood.
Do not hold screwdriver in mouth.
Do not touch any metal.
Red reset button is located on thermostat.
Push in reset.
If reset will not re-engage, then thermostat may be bad, or some other problem exists.
http://waterheatertimer.org/How-to-replace-thermostat-on-electric-water-heater.htmlScrew terminals on thermostat are live.
When finished, insulation and cover must be put back over thermostat so thermostat not exposed to cool air that will cause thermostat to misread tank temperature.
Put ear against tank to hear bubbly-fizzing sound that says water heater is working.
If water heater is leaking or wet, do not touch unless circuit breaker is turned off.
Electric water heater is fully repairable by homeowner.
ECO red reset button trips when upper thermostat senses overheating.
You many have underlying problem if reset continues tripping:
http://waterheatertimer.org/How-to-troubleshoot-electric-water-heater.html