The phrase "complete overhaul" refers to a thorough and comprehensive rebuilding, repairing or renovating of something. It implies that every aspect of the object is being addressed and nothing is left untouched. A complete overhaul can be done on anything from an engine in a car to a computer system, and it involves taking everything apart, fixing any problems, updating outdated components, and putting everything back together again so that it runs smoothly and efficiently once more. The goal of a complete overhaul is to restore the object to its optimal condition, making it like new again.