New wall charger problem, what could it be?

A

AC Question

New wall charger problem

Got a new usb wall charger recently. Charged my phone to 100% without problems and stopped charging. I thought it's just some feature to stop overcharging the battery. My battery is now at 80% and nothing happens when I plug in the charger. Could it really be that the charger broke after just one use or is there some kind of trick to this?