With this trick you unlock the shopping cart – without chip or euro piece! in the video you can see how it works.
It's really too annoying: Now you are right in front of the supermarket and realizes that you don't have the right change to unlock the car. And now? Push past the cash register and ask if you can change a bill? Go home just to get a euro piece? Fortunately, none of this is necessary: In the video you can see which trick you can use to unlock a shopping cart without a chip or coin in an emergency.