Diagnosis
The internal fuse on the main control board has blown, usually from a power surge or a short during cleaning.
How to Fix It
Check the power cord connection at the back of the unit. Unplug, then firmly reseat the cord where it inserts into the machine. It's a common point of failure.
If That Didn't Work
Let the unit sit unplugged for 30 minutes. This can sometimes reset the internal thermal overload protector if it tripped due to overheating.
Heads Up
If it died right after you added water or cleaned it, water might have leaked onto the electronics. In that case, you must let it dry out completely for 48+ hours before trying again.