peugeot 307 economy mode --- help?

I HAVE A 307 1.6 PETROL ON A 51 PLATE.
I UNLOCKED THE CAR GOT SOMETHING OUT, WENT BACK TO LOCK IT AND IT WOULDNT LOCK. I THEN TRIED STARTING THE CAR, IT DIDNT START. IT DISPLAYED ECONOMY MODE ACTIVE
THE ENGINE TURNS OVER BUT WONT START.
THE REMOTE CENTRAL LOCKING DOESNT WORK.
HOW CAN I GET IT OUT OF ECONOMY MODE AND GET IT TO START. I HAVE CHECKED FLUIDS AND CHANGED THE BATTERY.