Back last year, ground controllers lost control of Galaxy-15, which then started drifting in its geostationary orbit. This meant that it was moving into the positions of other satellites, and those other satellites had to have their orbits adjusted to avoid signal interference (the chances of an actual physical collision were too low to really worry about).
Apparently, it finally got disoriented without ground assistance, ended up with the solar panels no longer pointing at the sun, and shut down with no power. When the panels ended up pointing back at the sun again, it then powered back up, ground control managed to talk to it again, and they've applied software patches.
I suspect software patch #1 is "if you've not heard from ground control for $X hours, reboot".
Anyway, it's now heading back to the correct slot in the orbit.