As others have said...just keep reseating the water tank, 20-30 times may be necessary. You will see air bubble come up and until you stop seeing bubbles, keep dropping the tank into place. Eventually it will start to **** water from the tank filling the brewer with about 20oz of water. Wait a couple minutes for the water to heat and it will indicate ready and just select brew cup size. This will work. We just had the same problem today with our first breville coffee brewer and now it works great.
On the Breville XL600 the floating magnet stops the blinking lights until it doesn't after 10 years of delicious coffee. Why, because it looses magnetic strength over time. Sealed in place and not easily replaced if it is even available. Simply finger pressing it to the side of the water reservoir should do the trick.
SOLUTION (if the finger press works): Pass a small MAGNET in front of the coffee maker in the vicinity of the floating magnet in the water tank. This realigns the floating magnet briefly but may need to be repeated for each cup! Easily purchased at Amazon; try the Push Pins Magnets and use the rest for notes on your fridge. If the floating magnet is still too weak hold the added magnet in place while pushing the Brew button.
Try completely unplugging your pot and then plugging it back in. It is possible that this will reset the programming in your coffee pot. If this doesn’t work, I recommend calling Brevell customer service and they will either help you or probably send you another pot.
We got the Breville ESP6SXL as a gift from Crate and Barrel. I Put water in the tank put the tank in the machine and nothing but a loud vibration came out. I tried everything to get it to work and on one attempt noticed that a few small air bubbles come out when I dropped the tank in place. this means the air in the machine is creating a barrier that prevents the water from going into the machine. (priming process) I lifted the tank and pressed it down in and out for a while 20-30-50-100 times eventually drop by drop enough water gets into the machine to create a vaccum and this is what sucks the water from the tank into the machine. I suggest trying 20-30 times, make sure its heated up and turn it to brew, if it doesn't start working with 30 seconds, try another 20-30 times. I was going for a while and air bubbles kept coming out every time I dropped it back down. air bubbles were still coming out when it finally did start working so you don't have to get all the air out it just needs some water inside to create the proper vaccum. This will work, I tried calling Breville and was on hold forever... Good Luck Hope this helps Ken