Zareba is a commonly found brand, as they offer mass marketed products, including the inexpensive Fi Shock products found in box stores. Most internals of these units are now solid state, with LED lights, etc. This means YOU probably cannot service it yourself. If serviceable at all, you probably have to send it someplace, during which time you would be down and out of commission. Good for them and you that they have elected to send you a new unit.
What is encouraging is the visible response you are seeing from animals being exposed to it. They get it.......meaning they GET IT......the shock.......and downstream of that they GET IT.......having experienced a good shock, make the decision to stay away from it. They begin to practice avoidance. They realize that nothing on the other side of that fence is worth another jolt of juice.
Wild animals GET IT too.......which is why these fences work so well. None of these animals are intelligent enough to know what it was that caused that level of pain, but all of them are smart enough to know to stay away from it. No physical fence results in that level of respect. If a physical fence is built well enough to keep them out, they may eventually tire of the effort and frustration, but they don't respect it. Not so with E fences. They fear and respect those.