What could have happened is when the car was running last a sensor was on its way out and the ECU had been compensating, adjusting the running inline with the dodgy sensor. Now the ECU is back to factory standard it can't run with the duff sensor. Can happen. People have been know to go to a garage for a battery change and been told that it needs a new oxygen sensor! If it is driveable i'd personally be tempted to try give it a good drive and idle a few times see if it can re learn.

Good luck