If they are declaring mechanical failure, want to bet it's moon dust in the drive train or motors? That stuff is incredibly fine and very corrosive. According to the Apollo crews, it stinks as well.
Its back online
China Moon Rover Survives Lunar Night, 'Stands a Chance' of Recovery
It's alive! … Sort of. Reports of the death of China's first moon rover, Yutu, have been greatly exaggerated, according to the country's state-run media.
The Yutu moon rover, which suffered a potentially serious mechanical malfunction last month, is now awake and has apparently survived its second lunar night, China's Xinhua news agency reported today (Feb. 13).
Scientists on the ground are still trying to pinpoint the problems that caused the rover's mechanical malfunctions, but Yutu (which translates to "Jade Rabbit") can now receive signals normally
http://www.space.com/24688-china-moon-rover-survives.html