Good Question. I'm not sure about the details, but I think usual common sense dictates. I would first loosen brake fluid reservoir cap and remove excess fluid as to prevent overflow of reservoir fluid as caliper pistons retract. Maybe make sure that  the dust boot is free all the way around piston circumference so it is less likely to get twisted ,spooled up  and damaged, if  the pistons happens to turn and the dust boot rubber is really stuck to the piston groove.  I would try to stand in the back of vehicle and you should definitely hear something going with the electric motors during the retraction procedure  and maybe even try to assist with LIGHT inboard pressure against inboard brake pad with a  screw driver or small pry bar in case the electric motors are tired and you rather not be visiting an Audi dealer for a $1200 solution to what  a $12  hammer and drift used to  fix. LMAO.  I believe the pistons won't retract, just the actuator screws, and you still need to push pistons in (or rotate the pistons in if they have the notches for the piston tool)

 Yes! Leave ignition on during the process retract the epb then depends on the caliper type ie some winds back in clockwise some anti clockwise but most normally push back in like the front caliper. After you change the pads follow the instructions given by the tool.. difficulty 2 / 10

 Hi