I assume this is out of a HBL product. If so this is their internal part number and you will have to contact them for the manufacture's part number or a replacement unless someone on this forum has a parts list or schematic.
It is most likely a MOSFET given the application and package. A few quick measurements of the control voltage swing, supply voltage, and the current requirements for the relay you could identify whether it is a N or P channel and the current rating. From there finding a replacement would be easy.