In order to raise the commander of Cody and send it to the communication panel, where your ships can enter the battle with General Grivus, click the red button above.
Roy droids, including several elite models, will appear after you defeat Gryvus three times. Use either your light sword or blaster to fight with them.
The battle with Boss against General Grivus is currently at the last stage. Grivus will fall to the ground again. Now defeat the general once and for all, absorbing all his remaining health and crushing him during the last capture of the sword.
You must monitor your health, because during this battle several elite-diode soldiers will join the battle. The battle with the boss will end when its health indicator is completely exhausted for the fourth and last time. Complete the quest SO uncivilized in episode III: Revenge of the Sith, looking at the epistle video.
The completion of these four stages means that you have already defeated the boss. Congratulations.