Short answers, pulled from the story.
Fobos-Grunt failed because a programming error caused a simultaneous reboot of two working channels of the onboard computer, which meant the main propulsion unit never fired. The craft remained stranded in its initial low Earth orbit after launch on the 8th of November 2011 and never achieved the burns needed to set it on course for Mars.
Fobos-Grunt re-entered the atmosphere on the 15th of January 2012, over the Pacific Ocean. Russian military sources reported it fell 1,247 km west of Wellington Island, Chile, though civilian ballistic experts placed the debris zone further east, with a midpoint in the Goias state of Brazil.
Fobos-Grunt was designed to collect and return up to 200 grams of soil from the Martian moon Phobos. The return vehicle was scheduled to reach Earth in August 2014, which would have made it the first spacecraft to return a macroscopic sample from an extraterrestrial body since Luna 24 in 1976.
Fobos-Grunt carried the Chinese Mars orbiter Yinghuo-1, which weighed 115 kg and was to have been released into an 800 by 80,000 km equatorial orbit around Mars. The spacecraft also carried the Planetary Society's Living Interplanetary Flight Experiment and a radiation measurement experiment from the Bulgarian Academy of Sciences.
The total planned cost of the Fobos-Grunt mission was 5 billion rubles, equivalent to approximately 163 million U.S. dollars. Project funding for the 2009-2012 timeframe, including post-launch operations, was about 2.4 billion rubles.
Boomerang, also called Fobos-Grunt-2, is a proposed repeat Russian mission to return a soil sample from Phobos. Scientists and engineers at the Russian Space Research Institute and NPO Lavochkin called for the mission in January 2012 after the original failure. As of September 2023, Roscosmos stated it intends to launch Boomerang after 2030, as the first stage of a broader Mars sample return program called Mars-Grunt.