I recently had exhaust issues on 2001 Audi A6 Quattro

I took the car to and muffler shop and had some pipes replaced. And the car drove in the shop but it would not drive out... they put my old o2 sensor back in but in the process they messed up the wires going to the sensor and the car will not turn over. I asked around and some ppl said it could have fried my ecu. Any help would be nice.. thx

Asked by for the 2001 Audi A6 Quattro