Senseo keeps blinking?
If the light keeps blinking quickly, the water tank may not be seated properly on the machine, or the float in the water tank is broken.
The water tank contains a float with a small magnet inside. Because the float (the little tub) is not properly watertight, water gets in, causing the magnet to rust and expand. As a result, the float gets stuck. For a few euros you can buy a new magnet and the problem is solved!
Download the guide here to see how to replace the magnet.
Does your Senseo blink slowly?
If the Senseo keeps blinking slowly and does not heat up but does pump (turn it on and immediately press the buttons for one and two cups together), there is a good chance the boiler is broken. As a last possibility, it could be a defective circuit board.