The exit needle may be clogged. Refer to the manual (pg. 10) for directions on cleaning.
Clean the Keurig® K-Cup® holder if necessary and rinse under the faucet. Refer to the manual (pg. 10) for directions.
De-scale the brewer. Refer to the manual (pg. 11) for instructions.
Check to make sure there is water in the Hot Water Tank.
If the brewer is cold or frozen, wait for at least two hours for it to reach room temperature before powering it on.
Make sure the power button is pressed and illuminated.
Try plugging the brewer into an independent outlet. Be sure that it is plugged in securely.
If that does not work, try plugging it into a different outlet.