Likk Muak is a Mon Cal X-Wing pilot who was transporting an experimental R6 Astromech (yes via socket) out to Hoth. This R6 was programmed with a lot of sensitive data, essential to coordinating Rebel assets and safe locations throughout the galaxy.
En route the R9 realized that it was experiencing cascading issues with it's memory buffers and made an emergency stop in Tatooine. After the hyperspace outage, the droid shut itself down.
Likk made an emergency landing and was able to send a private distress signal to the Darklighter homestead (who passed on the distress message to the rebellion).