I learned early on in this game that mechanical units hate Force Lightning.
Since I've shunned every weapon once I got the lightsaber except for sniping and explosion fun, I've gotten very used to the lightsaber deflecting shots.
So what I did was this: I didn't know I could take out Galak's shield, so I just blocked his fire, slashed at his shield, and repeated until it went down.
Then I got close to him, deflected his fire, and used a few bars of force power hitting him with lightning.
He was toast in a few turns.
On the first try, no less.