Diagnosis
Power supply issue. This model uses an external AC adapter (wall wart), which is the most frequent point of failure.
How to Fix It
Check the power adapter and connections. First, ensure it's firmly plugged into both the wall outlet and the port on the back of the dispenser. Try a different wall outlet you know works.
If That Didn't Work
The AC adapter itself is likely dead. You need the specific ZeroWater replacement adapter (output: 9V DC, 1A, center-positive). A generic one with the wrong voltage/polarity can damage the unit.
Heads Up
Do not attempt to open the dispenser or bypass the adapter. There are no user-serviceable parts inside. If a new, correct adapter doesn't bring it to life, the control board is dead and you'll need to contact support.