“Most electronic shopping cart wheels listen for a 7.8 kHz signal from an underground wire to know when to lock and unlock. A management remote can send a different signal at 7.8 kHz to the wheel to unlock it. Since 7.8 kHz is in the audio range, you can use the parasitic EMF from your phone's speaker to ‘transmit’ a similar code by playing a crafted audio file.”

This sounds improbable but I needed to use it just now and it worked both times.

https://www.begaydocrime.com/