The single cup server runs over and grounds go everywhere.

Take it back must be in warranty.

The K-cup must be getting pierced on the top, where it lets the coffee grounds out into the cup during the brewing process. This usually means the K-cup isn't seated properly in the basket.

Ensure the kcups are being pierced by both the bottom and top needles. Be sure to check each kcup is thoroughly sealed before placing it in the brewer. Crushed or dented kcups may not brew properly.

The coffee can't get out.
There is a hollow metal pin that punches a hole in the bottom of the K cup to let the coffee out. Either it is missing or clogged.

Lower chamber is clogged. Clean as per manual page 18

Hi,

Here is a tip that I wrote that will give you some things to try that will helpyou get your Keurig coffee brewer workingagain.

Keurig CoffeeBrewer not making a full cup of Coffee
heatman101

Take out the used kcup and GENTLY explore the holder fitting. There should be a sharp point in the bottom that punctures the bottom of the kcup to allow the brew to flow out the spigot and into your cup. There also needs to be a sharp point on the top to punch a vent hole for the water to enter. It they aren't both open, coffee and grounds will spray everywhere. Take it apart and clean thoroughly as well.

The best way, if using ground coffee, 1 teaspoon per cup. Depends how big your coffee pot holds of water. So if you're planning to make coffee for 12 cups, just put in 12 teaspoons. Best Part is you can ground your own fresh ground coffee, or ground them at your Favorite Store, like Hazelnut etc.

You can buy the pouches. They make them for 4 cups 6 cups 8 cups, etc. (Like the ones they give you when you stay at the hotel). Fill the proper amount of water, for cups you're making.

My favorite are the single cups. Folgers makes them in regular and decaf. Look like tea bags, and they for 1 Medium Cup of Coffee. After you are done, just throw away.
Good Luck :0)