Citroen DS3 economy mode/stop vehicle/car won't start

I've recently had to replace the front side left spring and shock absorber whilst also replacing a cv boot on the car, I lost some transmission fluid in the process so had to top it up. This involves removing the battery on the ds3 to gain access to the fill hole, however after doing so and placing the battery back in I now get the warning light "stop vehicle" car in "economy mode". Trying to start the car I just get a clunk and there's no power to the windows or anywhere else if I want to perform a bsi reset as I was wondering if this would resolve the problem??