Diagnosis
Complete power failure points to a break in the internal wiring, a blown fuse on the control board, or a failed power supply module.
How to Fix It
Check the power cord thoroughly for any kinks, cuts, or damage, especially near the strain relief where it enters the fan base. Try a different, known-good wall outlet.
If That Didn't Work
The issue is internal. There is a small internal fuse on the main PCB. Accessing it requires full disassembly. If you're comfortable, you can check for continuity; if blown, it indicates a larger power surge or component failure.
Heads Up
This is not a user-serviceable issue beyond checking the cord. If the cord and outlet are good, the unit requires professional repair or replacement.