Diagnosis
The desk is in an anti-collision lockout. The control box detected an overload or obstruction during its last movement cycle.
How to Fix It
Unplug the desk from the wall outlet. Wait 60 seconds. Plug it back in. The desk will perform a short recalibration sequence. You should hear a single beep. The up/down buttons will now work.
If That Didn't Work
Check for anything physically jammed under the desk or between the leg columns. A stuck object can keep the system in lockout. Clear any obstruction and repeat the power cycle.
Heads Up
Avoid forcing items under the desk frame. The sensors are sensitive. Repeated lockouts can indicate a failing motor or control board.