You can understand a machine's sequence and make a useful fault report without opening its electrical enclosure. The practical boundary in this course is external observation and maintenance the exact model's manual assigns to the user.

Unplugging removes a mains connection when you have identified the correct plug. It does not remove every hazard: capacitors may retain charge, parts may remain hot, water may be under pressure and heavy assemblies may move. A power-button check cannot prove electrical safety.

Internal electrical testing, hardwired isolation, microwave internals and sealed refrigerant circuits require specialist competence. The useful decision is when to stop your checks and hand over the evidence.