Just a thought.... Not sure if the video online is of this incident but.....
There is a video from the cockpit of the windshield shorting out and arcing. The video is approximately 45 seconds long. It shows the short starting, growing, and the crew doing nothing but video.
I am wondering which "Emergency Procedure" they applied. There is a procedure for Window Arcing in the A320 QRH. The procedure is to pull circuit breakers as noted in the QRH. I can guarantee it does not say pull phone and start video.
If in fact they had performed the arcing procedure, perhaps they would not have had to conduct the Emergency Decent procedure nor deal with any missing FCU issues.