This is also from April, How the Air Force and SpaceX Saved Dragon from Doom.
"Right after spacecraft separation in low Earth orbit , a sudden and unexpected failure of the Dragon’s critical thrust pods had prevented three out of four from initializing and firing. The oxidizer pressure was low in three tanks. And the propulsion system is required to orient the craft for two way communication and to propel the Dragon to the orbiting lab complex."
"“The problem was a very tiny change to the check valves that serve the oxidizer tanks on Dragon.” Musk told Universe Today"
"“What we did was we were able to write some new software in real time and upload that to Dragon to build pressure upstream of the check valves and then released that pressure- to give it a kind of a kick,” Musk told me at a NASA media briefing."
"“But we had difficulty communicating with the spacecraft because it was in free drift in orbit...So we worked closely with the Air Force to get higher intensity, more powerful dishes to communicate with the spacecraft and upload the software to do the Heimlich pressure maneuver.”