The Japan Aerospace Exploration Agency says it has determined that the satellite's two solar arrays had broken off at their bases.
Contact was lost with the satellite on March 26, more than a month after its launch on February 17.
The space agency said yesterday that it would stop trying to fix the satellite and focus on figuring out what went wrong.
Japan's Kyodo News agency says that Japan spent about 31 billion yen (USD 290 million) on the project.