The Chinese lunar rover likely became crippled after hitting a rock while it navigated difficult terrain, according to a senior mainland scientist involved in the investigation into the breakdown.
Zhang Yuhua, deputy chief designer of Yutu or "Jade Rabbit", said the area where the rover landed was more challenging than expected, Xinhua reported.
The distribution of rocks made the area look "almost like a quarry", with at least four rocks at least 20cm high every 100 square metres, Zhang was quoted as saying. The six-wheel rover suffered a "mechanical abnormality" in January, about a month into its planned three-month mission.
Jade Rabbit, also known as Yutu, landed on the moon on December 14 - the first "soft landing" on the lunar surface since 1976. It first broke down on January 25.
Hopes were briefly raised when the lunar rover responded to controllers' commands - albeit with delays and difficulty - but it is currently incapable of activating its wheels or solar panels.
The breakdown had earlier been tied to the moon's low temperature, which caused a blockage in the power circuitry, preventing the driving mechanism from powering up.
Zhang, with the Shanghai Academy of Spaceflight Technology, said investigators had agreed the vehicle hit a rock large enough to cripple its movement.
Yutu remained "alive" and the scientific equipment it carried, such as its telescope, was still beaming back useful data, Zhang said. But it was losing its electrical capacity over time, and would eventually no longer be able to recharge itself with its solar panels.
Zhang said researchers were developing a prototype of the Chang'e 5, which is being designed to bring lunar samples back to earth. The Chang'e 4, carrying a rover similar to Yutu, is due to launch next year, and the Chang'e 5 in 2017, but that could change due to the setback.
The main purpose of the lunar programme was to send a large vehicle to the moon to retrieve samples and return them to earth in 2017.
One of the programme's long-term goals is to launch crewed missions to the moon and later establish a crewed lunar base.
No firm dates have been given, but some observers have said China could put a man on the moon in about a decade.