The shots didn't stop or defeat the undead but they slowed them down. Some shots even de-limbed them and they fell to the ground unable to continue. Some sergeant, Sergeant Pizzaglow, coordinated his men to form a defensive barrier and aim at the undead's heads and legs. That gave them a straight and powerful shot that usually amounted to slowing them down quicker, give the troopers girth to improve their manueverments and have newer troopers blast from ontop of the base to have the one's on the ground relocate within the base and lock it down. 

A Lieutenant Darkblue on the inside called to the Imperial Navy hovering near the planets orbit. He too, and with sufficient delegation from the forces within successfully got those Navy Destroyers/Dreadnoughts to target the vampire. With individual precision plasma shots the Navy would kill the vampire. 

They also believed the undead could be quarantined while the vampire was distracted by the fighter pilots. So, the troopers would have to continue all the while loading their frigates to lift off and leave the providence, so the Dreadnoughts/Destroyers could do their duty.

The TIE Pilot got his torso ripped open and blood flooded out. There was a yell of helplessness and then he fell forward on his controls and the TIE Defender crashed down. The other TIE Defenders opened fire on the whole situation.