Only one thruster pod of the four was working. In general, they need two pods working to do a set of maneuvers before deploying the solar panels. The software onboard sensed this and prevented the panels from deploying. Engineers on the ground noticed that the hardware used to open the panels was getting colder with time, so they decided to send up an override command to deploy the panels. This worked, and about 1 hour 40 minutes after launch, the panels were fully deployed and operational.
At around the same time, they were able to get a second thruster tank to pressurize, which was welcome news. Finally, about five hours after launch, SpaceX CEO Elon Musk announced that the final two thrusters were online and operational. As of this writing, they are still not fully powered up, but are expected to be soon.