How do I explain tech problems to frustrated non-technical people?

Knowing the fix and explaining it are two different skills, and the second is harder because it is not about the machine at all. It is about a frightened, frustrated person who does not speak your language and does not want a lecture. Drop the technical words entirely. They do not need to understand why; they need to know what will happen and that you have it handled. Speak in plain, calm terms, in the order they care about: here is what is wrong, here is what I will do, here is when you will be working again. Fewer words, more reassurance. And name their feeling before the fix. A simple I know this is frustrating, let us get you back up does more than any explanation. People relax when they feel understood, and a calm person can finally hear you. Meet the emotion first, then the problem, and the knots will start to loosen.