There is not much to a water heater. The main parts are the pressure relief valve (yours is working) and the electric circuit (this is malfunctioning.) There are many plumbers who do understand the few parts in the electrical circuit (they frequently replace elements – yours are working overtime.)
A most likely problem is that an element has failed and the current is blowing the breaker. The wiring or the limit control may be bad. Since the wiring diagram is usually on the cover of the element panel, an experienced, licensed plumber can repair the water heater. At worst you can have the plumber put in a new one.