“Why NASA Nearly Left Astronauts on the Moon” in July 1969, from Unveiled.
One of the astronauts broke off a switch accidentally, without which the engine could not be restarted.
Fortunately the astronauts manipulated a stump of the switch with a felt-tip pen.
Jeffrey Kluger wrote an article about this for Time in July 2019.
Lunar site selection map from Wikipedia embed, p.d., click for attribution.