First of all, I am new to this forum so hopefully I don't post up in the wrong section and hello all.

Secondly, I do work on my cars but I am not a professional, so I do have some technical.

Thirdly, English is my secondary language and also am very frustrated right now with this situation. So, please forgive me if I don't sound nice.

I have a 2007 Audi A6 with the electromagnetic rear brakes and to make long story short. I took off one of the rear caliper (this is my second time, was fine in the first) and on the process of installing it back to the car, I wrongly hit the "close" option on the VCDS while the caliper still outside and had the piston came loose (almost drop on the floor). It is giving me an error right now and no way I can retract it back in. Please help if you have a procedure of how to fix this issue.

Extra info: It parks at a friend's house right now so I can't get the error code, but like I stated. The motor pushed the piston all the way out and no way I can retract it.