Resetting the phase did not help us. But we did it differently. Three of us went in with a companion who could attack the droid behind the shield. After the companion was set to passive, the droid got out of the shield and we were able to attack it. After we defeated him, the shield went down and we could continue the mission normally

We tried the mission today, reset it three times and it would not progress too.

+1 for WP7 app. it would be really great if you guys do it.