These devices run software. Software is a series of instructions. Sometimes the instructions say to do things that are impossible. The machine can’t do it, or follow any more instructions because it is stuck trying to do something it can’t do. Going back the start lets it begin running new instructions again.
A good example would be like if in a chess game you saw both of your bishops on the same colour squares. Something has gone wrong somehow. You can’t keep playing, and you can’t remember the moves that got you to this point. You simply have to start the game again.
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